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BASIC CONCEPTS IN COMPUTING

WHAT IS A COMPUTER

A computer may be defined as an electronic device that has the capability of accepting and

processing data under the control of a stored program and producing output in the form of

information. This information may be in the form of sound, images, electronic signals, etc. and

may be stored within the computer or on an external storage device. Computers are not very

intelligent but they handle instructions flawlessly and fast. They must follow explicit directions

from both the user and the computer programmer. Computers are really nothing more than a very

powerful calculator with some great accessories. Applications like word processing and games are

just very complex mathematical problems.

SOFTWARE AND HARDWARE

The computer is made up of two basic components; software and hardware. The software

component consists of all the intangible parts of the computer, parts you cannot see or touch.

Whilst the hardware component consists of all parts that can be seen and touched. In other words

the hardware sits on your desk and executes the software instructions (programs). Without the

software the computer would be nothing more than a metal box.

HARDWARE COMPONENTS

The main hardware components that make the computer are:

System unit

Monitor

Keyboard

Mouse

There are also optional components that are used to enhance the performance of the computer but are

however not necessary for basic computer use. These components are called peripherals and are usually

attached to computers via interfaces. Among these, there are;

Multi-media speakers

Printers

Scanners

Webcams etc.

Generally the hardware components (main and peripheral) that make up a computer are grouped into

two basic categories based on the functions that they perform in relation to receiving and displaying

data/information.

Devices that aid in feeding data/information into the computer are called; input devices Examples include; keyboard, mouse, scanners, webcams, etc.

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Those that the computer uses to make data/information available to the user are called output devices. Examples include; monitor multi-media speakers, printers, etc.

A BRIEF DESCRIPTION OF THE MAIN HARDWARE COMPONENTS THAT MAKE UP THE COMPUTER

The system unit is the relatively big, mostly box-like object that usually sits on the desk aside the monitor.

The system unit houses the micro-processor which is the brain of the computer. It is the part that

receives all the instructions that are contained in a program and uses them to transform data into

information. Aside the micro-processor, another very important component that is housed in the system

unit is the memory chip. The memory chip serves as the working area of the computer. Theoretically this

is the area where the data is held prior to being processed. It is also the area where information is stored

after processing.

The monitor is a display device. Before we had only Cathode Ray Tube monitors which were bulky and

produced a substantial amount of radiation which was harmful to human health. However with the recent

advancement in technology they were replaced by the plasma screen monitors. These are smaller and do

not operate using the cathode ray tube technology.

The keyboard is the flatter rectangular device which uses an arrangement of buttons/keys to feed data

into the computer. Initially, prior to the introduction of the graphical user interface (GUI) it was the major

input device. However some of its functions can now be carried out using the mouse.

The mouse is more of a pointing device that uses either a track ball or a laser beam to move a pointer

across the screen of the monitor and perform various functions such as selecting and editing the contents

of objects.

OPERATING SYSTEM SOFTWARE AND SOFTWARE APPLICATINS

Similar to the hardware the software is also divided into two broad categories. These are the operating

system software and the application software.

OPERATING SYSTEM SOFTWARE

The operating system is an interface between the computer hardware, the user, and any other applications

software. It provides a platform on which smaller pieces of software (applications) can be executed. At first sight it

might seem that the operating system does very little, however, behind the scenes, the operating system is the one

in charge of monitoring the file systems, usage of resources, security, and other very important functions of the

computer. Examples of operating systems include; Windows XP, Windows 7, Ubuntu, Linux, etc.

APPLICATION SOFTWARE

Application software is used to refer to smaller computer programs that are designed to perform specific

tasks. These are user and platform specific. Examples of application software would include; Microsoft

word, VLC media player, Windows explorer, Need for speed most wanted, etc.

WORD PROCESSING

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INTRODUCTION TO AND EXAMPLES OF WORD PROCESSORS

Word processing as many of you would already know is one of the most common uses of computers.

Initially word processors were referred to as document preparation systems. The early word processors

date back to 1970s where they were mere stand alone office machines that combined key board text

entry and printing functions of an electric type writer with a dedicated processor and used for the

creation and printing of text. Through the years and with the aid of various technological advancements

word processors evolved from being simple monochrome standalone office machines with only the ability

to save documents on memory cards or diskettes, to powerful applications that included special features

such as a graphical user interface (GUI ), spell checking programs, increased formatting options and dot

format printing. The latest word processors are no longer stand alone machines. They are programs that

are installed and run on general purpose computers. Various versions of word processing applications can

be found in the software market. The major reason being that, they are software platform (operating

system) dependent. Examples of word processors are; Abiword, KWord, Openoffice, Libreoffice and LyX.

However the most popular word processing application is the Microsoft Word which comes with the

Microsoft Office Suite and runs on any of the Microsoft Operating systems. The latest version of this

application is Microsoft Office 2010. However for our tutorial we are going to use the 2007 version of this

application.

THE MICROSOFT WORD 2007 ENVIRONMENT

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CREATING A NEW WORD DOCUMENT

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Right click on the Microsoft Word icon. This may be found either as a shortcut on the desktop or

in the Microsoft Office file in the start menu.

in the home screen, click on the Microsoft Office button and select New from the context menu

that is displayed.

In the window that is displayed, select, Blank document and click the create button that is located

at the bottom right corner of the window.

Viola!!! Your new document has been created.

SAVING A WORD DOCUMENT

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The next best thing to do would be to save the newly created document. This can be done at any time but

it is advisable that users who do not use un-interrupted power supplies (UPS) perform this process once

in every five minutes to prevent loss of data during a power outage. Another point worth noting is that

there are two types of saves. If you right click on the Office button in the home screen of Microsoft Word,

in the context menu that is displayed there are two saving options, these are ; Save and Save As.

The Save As option is used to either save a document for the first time or, create a new copy of an

existing document.

The save option is used to update or save changes to an already existing document.

Below are the steps to be followed when performing the save as and then the save operations.

SAVE AS

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Left click on the Office button and select the Save as button from the context menu.

In the resulting window select the location on the computer where you would like to save your file

and enter the file name and select the format in which you would like to save your file.

Type a new file name for your file in the file name text box

Right click the Save button which is as usual at the bottom of the screen to save the document.

SAVE

Right click on the Office button to open the office context menu

Click on the Save button to add changes to the already existing document

OPENING AN EXISTING DOCUMENT

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To open an existing document in Microsoft word, follow the procedure below;

Open Microsoft office and click on the Office button.

Either select the file that you want to open from recent documents, these are displayed in a side

window at the right of the thumbnails in the office menu, or click the Open icon to display the

open file dialogue box.

In the dialogue box displayed navigate to the word file that you would like to open Click the Open

button which is at the bottom right corner of the screen.

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TEXT ALIGNMENT

By default the text in word is left aligned. In other words each new line of text begins at the left margin of

your page. Anther way of saying this is; the text is left justified. This however is not static and can be

changed. The alignment buttons in the paragraph group of the home tab allow us to make changes to the

way that the text is alligned.

The images on each button give a good idea of the type of allignment that is.

The first button is the left align button. It alligns all the typed text to the left margin of the sheet

The second button is the center align button that is used to centre each line of text in the middle

+of the sheet

The third button is the right align button and is the exact opposite of the left allign button. This

button alligns each line of text to the right margin of the sheet.

The last button in the collection is the justification button and is used to justify the text in such a

way that not only is it placed in the middle of the screen but also adjust the spaces between

words.

In order to change the alignment of text in your document, all that you have to do is select the text that

you want to justify and click on any of the align buttons that best suit your purpose.

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WORD LAYOUT/PAGE ORIENTATION

There are two ways of orienting a page in Microsoft word. These are the portrait and the landscape

layouts. In the portrait layout the page has more horizontal space as compared to vertical space. In the

landscape orientation the page has more horizontal space than vertical space. The layouts you select for

your document are subject to your needs. The portrait layout is the default layout for all new word

documents and is usually suitable for most cases such as typing out letters. The landscape layout may

come in handy when the page contains tables that have a small number of rows and a large number of

columns.

Portrait layout landscape layout

To change the layout of your word document;

Select the page layout tab and click on the orientation icon from the drop down menu.

Select the either the landscape or portrait layout to apply.

ADJUSTING MARGINS IN WORD

Margins are the blank spaces around the edges of your document and although objects such as images

are inserted into the printable area of the documents, some items may be inserted into the margins. An

example of such an insertion is the insertion of page numbers either at the top or the bottom of the page.

To change the margins in your document, follow the procedure below.

Click on the page layout tab.

Click on the margins thumbnail

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From the drop down menu select the most desirable thumbnail margin

NB: Changes would be applied to all pages.

If however none of the preset margin types fit your purpose then;

Click on the customs margin text at the bottom of the margins layout drop down menu.

Make the necessary adjustments

Click the OK button to apply changes

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The top area of the window allows us to adjust the margin size for top, bottom, left and right of the page.

There are also input boxes for you to specify a gutter margin. You would use a gutter margin to add extra

space to the side or top margin of a document you plan to bind. A gutter margin ensures that text isnt

obscured by the binding.

In a case where the changes you made do not seem to suit your purposes, click on the default button to

set all the parameters to default.

GRAPHICS IN WORD

INSERTING IMAGE FILES

The types of images that you can insert into you Microsoft Word document are numerous. You can insert

Clip Art from Microsofts Clip gallery, you can insert images crated from graphic applications like adobe

Photoshop, photos you take with your digital camera, scanned images and images obtained from the

internet. If you are using images from the internet make sure that you have permission to use them first.

To insert images and pictures stored on your computer

Click the insert tab

Select picture from the thumbnails displayed

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In the insert picture dialogue box that appears, navigate to the location of the picture file that you

want to insert.

Select the picture that you want to insert by left clicking on it

Click on the insert button at the bottom right corner of the insert image dialogue box to insert the

image.

The image is inserted at the position of the cursor. For this reason it is not a bad idea to click the

return/enter key a few times before inserting your image to make room for it.

The picture can be resized to suit your demands. This can be done by left clicking on and holding any of

the four small boxes (handles) that you see on each of its borders or any of the circles on its corners. The

image could also be rotated by left clicking on the small green circle that is attached to the image by a

vertical line and moving the mouse in ether a clockwise or an anticlockwise manner.

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DELETING IMAGE FILES

To delete an image file;

Left click on the image to select it

Push the delete button to delete the image from the document.

TEXT WRAPPING

By default when an image is inserted into a document it is inline. However , this arrangement doesnt look

as good as it could. In order to change the text wrappoing property of he image .

Select the image

In the picture tools contextual tab select the text wrapping thumbnail

Select the option that best meets your requirements from the drop down list

The options that are displayed have the following characteristics.

Inline with text - the default setting. The image is part of the line of text on which is inserted.

Square- the text flows around the image

Tight the margins between the image and the text are smaller

Top and bottom text appears at the top and bottom of the image

In front of the text - the image actually obscure the text that it is in front of.

DRAWING TOOLS

Incorporated into microsoft word is a feature that allows the user to insert shapes, modify the

appearance of text and draw lines in order to make emphasis or create diagrams.

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INSERTING SHAPES AND CREATING LINES

This feature of the application is found in the insert option of the home tab. To use it.

Click on the insert option in the home tab

Go over to the illustration collection

Left click on the shapes thumbnail

If you followed the procedure above correctly, a context menu would be displayed showing the line and

shape alternatives that can be inserted into your document. To insert a line;

Click on any of the line options in the context menu to select it.

Move over to the position in your document where you would like to place the line.

Move the pointer( which is supposed to change to a plus sign) to the position where you would

like your line to begin

left clik once at that position

Now move the cursor to the position where you would like your line to end

Right click once at that position

To adjust the positon of the line

left click once on the line

left click on the green circle that is at the end of the line that you would like to adjust

Whilst holding down the right click button drag the end of the line to the required length

Leave the mouse button

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To move the line or arrow to another position

Move your pointer over the line untill it turns to a plus wth arrows at the end

Left click on the line or arrow

Whilst holding down the left mouse button, drag the line to the location within your document

where you would like it to be.

Leave the left mouse button to drop the image.

To insert a shape

Click on the insert option in the home tab

Go over to the illustration collection

Left click on the shapes thumbnail

Directly below the lines collection are the shapes collections. To insert any of the shapes;

Left click on the shape that you would like to insert

Left click on the location within your document where you would like the shape to be.

The procedure to resize or rotate a shape is the same as the procedure used to resize or rotae an image

file.

Sometimes after inserting an object it might be nessessary to insert a text into the object. To do this;

Right click on the object

From the context menu, select the add text option

Type your text in the text box that appears

When you are done click any where in the document aside the object to exit.

INSERTING WORD ART

Word art is a special feature in microsoft word that allows us to insert specially formatted text into the

document. This feature comes in handy when we are designing notices or cards. To insert a text

formatted by word art;

Select the insert option on menu tab

Select the WordArt thumbnail from the text collection by clicking on it

From the drop down menu, select any of the word art formats that best suit your purpose by

clicking on it

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In the window that is displayed, type your text in the section that says type text here

Click the ok button to insert the text

CREATING TABLES IN WORD

Another very useful feature in microsoft word is the insert table feature. It is very common to have tables

as part of documents, especially if the document is a report or a budget of some sort. To insert a table

into a word document;

Left click on the insert tab

In the tables collection select the table thumbnail

In the drop down menu you would see a box matrix. Each row of boxes represents a row on your table

and each column of boxes represents a column in your table.

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Left click on the left, topmost box and drag the cursor to select the required number of rows and

columns

You should see a corresponding table being created on the active page of your document

alongside.

When you have selected the required numberof rows and columns, click on the box over which

your curses is to finalize the creation of the table.

Text is inserted into the cells of the table by left clicking on the cells. The text in each cell can also be

formatted just as the text in an ordinary document, page where the cell borders serve as the page

margins.

The rows and columns of the table can also be resized to suit the requirements of the user. To do that;

Move the cursor to the cell border that you would like to move untill it changes into two sided

arrows.

Hold down the left mousebutton and drag the dotted line to the position where you would like the

border to end.

Leave the button to effect the changes

PRINTING IN WORD

After the document is ready it might be nessesary to create a hard (printed ) copy of it. Printing is another

option that is available in Microsoft word. To print out a document in word;

Left click on the office button

Place the pointer over the print thumbnail

Select the print preview thumbnail in the context menu that is displayed on the right

In the print preview you are shown what the document would look like after it has been printed. Here

from the menu tab you can make changes to the margins and orientation of the page to suit your

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purposes. When you have edited the page layout click on the print tab to display the print window and

then left click the print button to begin printing the document.

Occasionally there might be times when you would want to print only a page out of the entire document.

To do this;

Find that page in the document and make it the active page by left clicking on it

Go to the print menu through the office button and select the print option

In the print window, go the page range and select the current page option

Left click the print button to begin printing

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INTRODUCTION TO AND TYPES OF SPREADSHEET APPLICATIONS

Lets begin our introduction by answering this question. What is a spreadsheet??? The answer to that is

very simple; a spreadsheet is a grid that organises data into rows and columns. Spreadsheet applications

( sometimes referred to simply as spreadsheets ) are computer programs that enable us to create and

manipulate spreadsheets electronically. In a spreadsheet application each value sits in a cell. You can

define what kind of data you have in each cell and how different cells depend on one another.You can

also create formulas that would enable you to manipulate this data with ease and accuracy. Examples of

spreadsheet applications are; lotus 1,2,3 and Microsoft Excel.

Excel enables you to build a calculation by creating a formula that specifies what values to calculate and

what mathematical operators to use to perform the calculation. Excel also offers functions, predesigned

formulas that perform more complex calculations, such as calculating accrued interest. Excel not only

provides tools to assist you in building and error-checking spreadsheet formulas but also gives you many

easy choices for formatting the data to make it more readable and professional. These include;

Worksheets. Within each file, you can divide and organize a large volume of data across multiple

worksheets or pages of information in the file.

Ranges. You can assign a name to a section of data on a worksheet so that you can later select

that area by name, or use the name in a formula to save time.

Number and Date Value Formatting. You can apply a number format that defines how Excel

should display a number, indicating details such as how many decimal points should appear and

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whether a percentage or dollar sign should be included. You also can apply a date format to

determine how a date appears.

Charts. Translate your data into a meaningful image by creating a chart in Excel. Excel offers

dozens of chart types, layouts, and formats to help you present your results in the clearest way.

INTRODUCTION TO MICROSOFT EXCEL

When you first launch excel 2007, the program opens up the first of the three new worksheets (named

sheet1) in a new workbook file (named Book 1) inside a program window such as the one shown in figure

The excel program window containing this worksheet of the workbook is made up of the following

components;

Office Button: When clicked, this button opens a pull-down menu containing all the file-related

commands including Save, Open, Print, and Exit as well as the Excel Options button that enables you to

change Excels default settings.

Quick Access toolbar: You can click the Save, Undo, and Redo buttons to perform common tasks to

save your work and undo and redo editing changes. You can also click the Customize Quick Access Toolbar

button to the immediate right of the Redo button to open a drop-down menu containing additional

common commands such New, Open, Quick Print, and so on as well as to customize the toolbar, change

its position, and minimize the Ribbon.

Ribbon: Most Excel commands are contained in the Ribbon. They are arranged into a series of tabs

ranging from Home through View.

Formula bar: The address of the current cell along with the contents of that cell appears in this bar.

Worksheet area: This area contains all the cells of the current worksheet identified by column

headings, using letters along the top, and row headings, using numbers along the left edge with tabs for

selecting new worksheets. You use a horizontal scroll bar on the bottom to move left and right through

the sheet and a vertical scroll bar on the right edge to move up and down through the sheet.

Status bar: This bar keeps you informed of the programs current mode and any special keys you

engage, and enables you to select a new worksheet view and to zoom in and out on the worksheet.

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Making the most of the Office Button

At the very top of the Excel 2007 program window, you find the Office Button (the round one with the

Office four-color icon in the very upper-left corner of the screen) followed immediately by the Quick

Access toolbar. When you click the Office Button, a pull-down menu similar to the one shown in Figure 1-

2 appears. This menu contains all the commands you need for working with Excel workbook files, such as

saving, opening, and closing files. In addition, this pull-down menu contains an Excel Options button that

you can select to change the programs settings and an Exit Excel button that you can select when youre

ready to shut down the program.

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STRUCTURE OF THE SPREADSHEET

The working area in the image above represents the worksheet. As can be seen, it consists of rows and

columns. Each of these rows and columns can be uniquely referenced/identified by the row and column

number. The rows are numbered using the normal number system (0,1,2,3, ). The columns however are

referenced using alphabets, A, B, C , . . . When the full length of the alphabet is exhausted, combinations

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of letters are used to reference each column, ie. AA AZ, BA- BZ, CA CZ, . . . This referencing ability of

excel becomes very handy when values in cells are to be generated based on values that have been

entered into some other cells.

The intersection of a row and a column forms a cell. each cell in excel is capable of holding values. Each

cell can be formatted to suit the type of value that it is meant to hold. Examples of format types include;

date, general, text, etc.

The excel spreadsheet consists of several worksheets. Only one worksheet can be active at a time. To

switch between worksheet, simply select it by clicking on it in the bar right above the status bar.

FORMATTING THE SPREADSHEET

The general appearance of the spreadsheet working area can be altered to suit your purposes. Several

formatting features are available and are discussed in the section below

SELECTING RANGES

One or several cells can be selected based on the user requirements and formated as necessary. To select

a range of cells;

Left click on the leftmost, topmost cell within the range of cells that you would like to select.

Whilst holding down the left mouse button, drug the cursor to the rightmost, bottommost cell

within the range

Leave the left mouse button.

If you are using the 2007 version of Excel, the selected range of cells would be highlighted in blue. Now

you can apply the formatting to these cells.

FORMATTING BORDER LINES

Several aspects of the cell can be formatted using the options availabe in the home tab, the first that we

would be considering is the border outline.

The borders of a cell or a range of cells refers to the the border lines that envelope it/them from the top,

bottom, left and right directions. To change the border lines;

Select the cells whose border line you would like to change.

Left click on the border format bordres thumb which can be found in the font collection of the

home thub.

From the drop down menu select and apply the type of border format that suits you most by left

clicking on it.

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MERGING CELLS

Sometimes, when creating reports for printing it might be necessary (for aesthetic purposes) to

transform a few cells into one cell. this process is called merging. It is worth noting that merging of

cells can only be carried out on several cells and not just one cell.

To merge cells

Select the range of cells that you would like to merge

From the alignment tools collection click on the merge and centre thumb.

In case an error has been made, the process can be undone by clicking on the merged cells and clicking on

the merge and center thumb once again.

TEXT ALIGNMENT

The text in each cell can be aligned to suit the users choice. Available options are left, right, centre justify.

To align the text in a cell or a range of cells;

Select the range of cells (where applicable).

In the allignment collection select and apply the required allignment format by left clicking on the

appropriate tab

CHANGING THE NUMBER OF DECIMAL PLACES SHOWN

Since most of the data that we work with in excel is numerical. A tool has been provided that can be used

to define the number of decimal places that are shown for a figure in a cell or a range of cells. To change

the number of decimal places that a figure is rounded up to, for a cell or a range of cells;

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Select the range (where applicable)

From the number tools collection, click on either the increase or decrease decimal thumbs to

either increase or decrease the number of the decimal places.

e cell active by left cliking on itvalue

Left click away from the cell

ANALYZING DATA

After learning how to enter data the next topic would be on how to analyze the data that we have

entered. In our tutorial we would be considering some of the inbuilt functions, we would be learning how

to;

Sort data in ascending and descending order

Filtering data

Auto sum

Average

Counting numbers

Maximum value

Minimum value

All these are inbuilt data analysis tools that have been incorporated into Excel.

SORTING DATA

The sorting tool is used to sort the records in the database based on the values entered into a specific

column. This ordering may be ascending or descending and is defined prior to sorting. To sort data;

Select the column base don which you would like to perform your search

From the editing tools collection in the home tab select the sort and search thumb

Left click on the order in which you would like your data to be sorted. These may be ascending ( A-

Z ) or descending (Z-A ).

A message box pops up asking you if you would like to expand the sorting to neighbouring cells.

NB: if you choose to expand your selection then all neighbouring columns in your data base that

hold data would be sorted alongside the selected column based on the data entries in the selected

column. However if you choose to continue sorting with the current selection then only the data

entries in the selected column would be sorted in the order selected.

Select the desired option from the message box and click the sort button.

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FILTERING DATA

Sometimes it may become necessary to display some rows or hide others based on some entries made

into a column. For example, this feature would come very handy if we are trying to generate a list of all

the studnts in the class who have second class upper from the general class list. To filter data;

Select the column based on which you would like to perform the sorting

From the editing tools collection in the home tab select the sort and search thumb

From the drop down options menu select the filter thumb by left clicking on it.

This action places a show all button on the first record in the column you selected

By left clicking on that button, the following message box is shown

In this box you are given the option of selecting the records that you would want to be shown

based on the whether they contain any of the ticked values or not.

Select the desired values and left click ok to effect the change

AUTO SUM, AVERAGE, COUNT NUMBERS, MAXIMUM AND MINIMUM VALUES

All these fuctions are available under the sum icon which can be found in the editing tools collection of

the hometab. They do literary what they it is said they do. To perform any of the above mentioned

functions;

Select the range cells in a particular row or column

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Left click on the arrow by the sigma sign in the editing tools collection in the home tab.

From the drop down menu select the required tool by left clicking on it.

MICROSOFT POWERPOINT

INTRODUCTION

PowerPoint is the powerful and ubiquitous presentation program from Microsoft. It gives you the facility

to create stunning presentations that incorporate video and PowerPoint animations. The image editing

capabilities that PowerPoint offers get better and better with every new version. Starting to learn

Microsoft PowerPoint can seem like a daunting task if you are not familiar with its environment. The

tutorials you would go through would take you by the hand and teach you the basics of using this

application.

CREATING A NEW PRESENTATION

There are a variety of ways of creating your PowerPoint presentations and one of them is to start from

scratch, in doing so you are creating your presentation from a blank presentation and you have much

more flexibility over how it looks.

The first step as usual is to open the PowerPoint application by clicking on its icon. The power point icon

looks something like this and can be found in the Microsoft office suite.

In the window that appears click on the office button and select the new thumb

Ensure that blank presentation is selected. You can click on the thumbnail image to select it if it

isnt and then click create. A new presentation based on a blank presentation opens for you to

start work on. As soon as you can, save the presentation so you dont lose any changes

NB: Remember that the save procedure is the same for all applications that form the Microsoft office

suite.

POWERPOINT BASIC TASKS

ADDING SLIDES

There are a couple of ways to add a new slide. In each way, the slide that is currently selected is a

important as the new slide will be placed after the selected one. This means that if you want to insert a

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slide before the end of the presentation, you will need to select the slide that appears before the one you

want to insert. To select the slide, just click on it. You can select the slide in whichever view you happen to

be using, whether it is slides view or outline view. Once you have selected;

Select the new slide option that is found under the slides thumb in the home tab

You will notice that the new slides button is in two halves, if you click on the new slide button, the default

title and content type slide will be added. If, instead, you click the bottom half of the button, you will be

able to select what type of slide is added.

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Once the new slide has been added, you can click into one of the editable content boxes to make your

changes.

The keyboard shortcut for adding a new slide is ctrl + m.

DELETING SLIDES

You have learned how to add slides to a presentation; the time has come to learn how to delete

unwanted slides. Deleting slides can be performed in three ways. Select the slide and then

Press the delete key on the keyboard

Press the backspace key on the keyboard

Right click on the slide and select Delete Slide

Also, there are a variety of places that you can delete the slide in question. The easiest way is to work in

normal view (on the view tab, in the presentations views group, click normal). You can then work on

either slides or outline tab: find and select the slide you want to delete and then press the delete key, you

can select multiple slides by holding down the control key as you click on additional slides. If you press the

delete key now, you will delete all the selected slides. If you have a group of slides that run in sequence,

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you can select them all by selecting the first one and then holding down the shift key whilst you click on

the last slide.

If you have many slides to delete, you may find it easier from an organizational point of view to work in

slide sorter view. The same process applies: select single or multiple slides and then press the delete key.

MOVING SLIDES

You have spent time planning how you want your presentation to look and you have painstakingly

designed its look and feel. You have taken great care with every stylish slide you have added, but at the

last moment you realize that slide six actually belongs before slide five! What do you do, start from

scratch??? There is no need. All you have to do is move the slide. You can change the sequence of your

slides by moving them around your presentation.

To move a slide in your presentation, all you have to do is drag and drop it where you need it. As you drag

the slide, you should see an insertion point that looks like either a horizontal or vertical line, depending

on which PowerPoint view you are using, that tells you where your slide will appear.

You can move several slides around as a group by selecting them all first and then dragging and dropping

them. To select multiple slides, hold down the control key and the keyboard as you click on additional

slides. Alternatively if the slides you need to select occur in an unbroken sequence, you can select the first

slide and then hold down the shift key as you click on the last slide.

MOVING SLIDES WITH KEYBOARD SHORTCUTS

Another way to move slides around is to cut and paste them. Select the slide(s) you want to move, right

click on the selection and select cut. Select the slide that is positioned before where you want the slide to

go and then right click and select paste. The slide(s) will appear after the selected slide. If you want to

speed things up you can use keyboard shortcuts; select the side you want to move, press ctrl + x to cut

and then ctrl + v to paste it.

POWERPOINT VIEWS

There are six different views you can use to look at your PowerPoint presentation and each one has its

advantages over the others. The default view in PowerPoint is normal view. This means that when you

start PowerPoint, and as long as you dont change the view, you will be working in normal view. There are

two places to change to a different view; at the top of the left side panel and at the bottom of the

workspace to the right (next to the zoom slider). OK, make that three, since you can also see the

presentation views on the view tab.

To change the slides views view or outline view, click the corresponding tab at the top of the left side

panel.

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Slides View and Outline View

To change to any other PowerPoint view, use the small toolbar at the bottom:

Normal view, slide sorter view, reading view, slide show

Here is an explanation of how you should use the different views:

POWERPOINT VIEW DESCRIPTION

Slides view This is a great place to view the slides in your presentation as thumbnail-sized images while you edit l the thumbnails make it easy for you to navigate through your presentations and to see the effect of any design changes. You can also easily rearrange, add, or delete slides here

Outline view This is a great place to start writing your content, to capture your ideas , plan how you want to present them and move slides and text around. The outline tab shows your slide text in outline form

Normal view Normal vies is the main editing view, where you write and design your presentations

Slide sorter view Slide sorter view gives you a view of your slides in thumbnail form. This view makes it easy for you to sort and organize the sequence of your slides as you create your presentation and then also as you prepare your presentation for printing.

Reading view Use reading view to deliver your presentations not to an audience but instead to someone viewing your presentation on their own computer. Or use reading view on your own computer when you want to view a presentation not in a full-screen slide show view, but in a window with simple controls that make the presentation easy to review. You can always switch from reading view to one of the other views if you want to change the presentation.

Slide show view Use the slide show view to deliver your presentation to your audience. Slide show view occupies the full computer screen, exactly like an actual presentation. In this view, you see your presentation the way your audience will/ you can see how your graphics, timings, movies, animated effects, and transition effects will look during the actual presentation.

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MODIFYING BCKGROUNDS

For the background to your PowerPoint presentation, you can specify the following;

A solid fill

A gradient fill

A picture texture fill

To change your presentation background

Click on format background

Click on background styles

Select background

And then click on design

Alternatively, you can right click on a free area on a slide (and area that does not contain an object) and

then select format background from there.

You should now see the format background window

Ensure that the fill tab is selected (as in the image above) and then make the changes according to what

kind of background you want for your presentation.

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SOLID FILL

To specify a solid fill color, ensure that the appropriate radio button is selected and then click on the fill

color swatch, a panel is displayed for you select a color.

The colors in the main part of the grid are all theme colors, so if you select one you can be pretty

confident that the background will blend in well with the rest of the presentations colors. At the bottom

of the color selection panel are standard colors and if you want even more colors to choose from, you can

click more colors at the bottom.

GRADIENT FILL

A gradient is the smooth transition of one color into another

When this option is selected, you can choose from a selection of readymade gradients by clicking on the

preset colors button. Alternatively, you can exercise more control by defining the gradient yourself. If you

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do this, you will need to tell PowerPoint whether the gradient is linear, radial, rectangular, path or shade

from title. Additionally you will need to specify the gradient (with the gradient stops) and the properties

of each color in the gradient, these properties include what the color is, how bright and how transparent

it is.

PICTURE OR TEXTURE FILL

When specifying a picture or texture fill for your PowerPoint background, you are actually using a picture

as the background.

PowerPoint comes with some built in textures you can use, or you can select an image that is stored on

your hard drive. When you select an image in this way, you can choose to have the image appearing just

once in the background or to have it repeating like a texture. As you can see from the screenshot, there

are many outer attributes you can use to set that control the pictures appearance.

RESETTING THE POWERPOINT BACKGROUND

If you decide to reset your background, but you have made so many changes that it would take too long

to reverse each one. Or you can use the reset background button at the bottom of the format background

window. You can also tell PowerPoint to apply the background you just designed to all slides in the

presentation using the apply to all button. If you dont apply the background to all slides, then only the

currently selected slide is affected.

POWERPOINT TEXT

ADDING A TEXTBOX

When adding text to their PowerPoint presentations, many people limit themselves to using only the

placeholder boxes that are present by default when you add a new slide. For example when you add a

title and a content slide, there is always a title placeholder in which you will see the words Click to add

text. It is then a simple case of clicking into each of those boxes and then typing your content

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However, another way of adding text that gives you more flexibility over positioning is to add a textbox.

To add a textbox simply click on the textbox thumb in the in the text tools collection which can be found

under the insert tab. The cursor is supposed to change to;

Left click with the mouse and drag out the textbox. Once the text box has been drawn, you can start

typing in it. When you drag out you initial text box, it retains its width. But the height contracts

temporarily to be the height of one line of text. When you type multiple lines, the height will adjust to fit

but the width of the textbox will remain the same.

This is what the textbox looks like.

You can see the resizing handles at each corner and also halfway along each edge, you can resize the

textbox by clicking and dragging on any of those handles.

You can actually move the textbox to any position on the slide by simply moving the cursor over it until it

turn into something like this;

And then whilst holding the left mouse button down, dragging it to the desired position.

CONTENT PLACEHOLDERS

Microsoft PowerPoint placeholders are boxes with dotted borders that contain content and reside within

a slide layout. All built-in slide layouts that come with the application contain content placeholders. If you

click on the bottom half of the new slide button, PowerPoint displays all the slide layouts you can insert

and on each you can see content placeholders

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If you insert a two content slide layout, for example, you will get three placeholders; one for the slides

title and two for the content. To add your own text, click in a placeholder and start typing. You can style

the text however you please using the usual formatting options.

But how does PowerPoint know what placeholders should appear on each slide? This is determined by

the slide master. If you click on the slide master which can be found under the master view in the views

collection, you will see all the slide layouts available for use in your presentation. The layout in each is

controlled by, among other things, the content placeholders on them.

Click on any slide layout to select it and you will see the placeholders already present. You can add new

placeholders by clicking Insert Placeholder in the master layout group of the slide master tab. If you click

the top half of the button you will add the same placeholders as you added last time, whereas if you click

the bottom half; you get a choice of placeholders to add. Usually you will not add content placeholders to

exiting slide layouts (though you might). Placeholders are more useful when you create a new slide

layout.

FORMATTING TEXT

Most of the time, you will probably leave the text you type in your PowerPoint presentation as its without

formatting it. However, sometimes you might like to style certain pieces of text so that it stands out.

To format some text first of all select it as you move the cursor, the mini toolbar appears as if by magic.

The mini toolbar contains some of the more commonly used formatting commands that PowerPoint

guesses you are likely to use. Using it you can bold text, italicize it and do various other text formatting

tasks, all at the click of a button. You will probably be familiar with all of the commands available on the

mini toolbar.

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If you want to apply more adventurous formatting head over to the ribbon. When you select text, the

format contextual tab appears. On this tab are many different formatting functions. Let us get to grips

with formatting text by running through a quick example.

GRAPHICS

INSERT POWERPOINT I IMAGE

To insert an image in PowerPoint, click on the images thumb in the insert collection. you can see that

there are four different types of images you can insert here, and we will explore each one now.

INSERT IMAGE

If you have an image, for example a photo you have taken, on your PCs hard drive, you would click on the

picture button. Then you would navigate to the place in your hard drive where the picture was located

and either double click on it or select it and then click insert.

INSERT CLIP ART

When you click the clip art button, the clip art panel opens on the right of the workspace.

We can use this panel to search for clip art images of certain things. In the image above I searched for

telephone and found four related images. To narrow down the search, you can click on the results

should be drop down list and select one of the categories of;

Illustrations

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Photograph

Videos

Audios

To insert any of the images just click on it.

ADDING TRANSITIONS TO POWERPOINT PRESENTATIONS

In Microsoft PowerPoint, slide transitions are motion effects that occur in slide show view when you

move from one slide to the next during a presentation. You can control the speed, add sound and even

customize the properties of transitions effects. To add a transition first of all select a slide in the left hand

panel that contains the slides and outline tabs. The transition will occur immediately before the selected

slide is displayed. To select a transition just click on the transition thumb under the transitions, under the

animations tab.

When you hover over a thumbnail image of a transition, you can see a live preview of it applied to your

slide. When you move the cursor away, the preview is removed.

If, after having applied a transition to the selected slide, you decide that you want the transition applied

to all slides, click on the Apply To All button in the timing group on the same tab.

POWERPOINT ANIMATIONS

To add an animation to an object in Microsoft PowerPoint, first of all select the object, then click

animation in the ribbon to see all the animation options that you have at your disposal. We can see a few

thumbnail images representing entrance effects in the animation group.

To preview any of the animations above all you have to do is to hover your mouse over the option. You

can see a preview of what that animation would look like, if applied. The animation plays once. You also

get to see what the animation looks like when you actually apply it to the object. If you want to see a

preview of the animation at any other time, click the preview button to the far left of the animations tab.

All slides that include an animation display a wooshing star next to the slide in slide view and slide sorter

view.

To remove an animation from an object, click on the dialogue box launcher and select none at the top.

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SLIDE SHOW PRESENTATION

At any time during the PowerPoint presentation, you can run it to see a preview. This will show you how

you presentation looks when you run it for real.

There are several ways to start your presentation. You can;

Click on the slide show button at the bottom of your workspace

Press F5

Click slide show in the start slide shown of the ribbon, and then choose the most appropriate way

to run your slide show.

Generally speaking you have two options: to start the presentation from the current slide, of from the

beginning.

MULTIMEDIA

INTRODUCTION

With the introduction of the graphical user interface (GUI), the possible uses of computers increased

rapidly. One of the areas that benefitted most from this was the area of multimedia applications.

Multimedia refers to a combination of text, audio, still images, animation, video, and interactivity content

forms. Initially access to these media types were restricted to dedicated devices however with time these

functionalities were incorporated into personal computers. Today it is almost impossible to find a

computer that would not have a media player or a picture viewer.

Since this is a basic introduction we would only consider the use of the windows medial player in playing

media (sound and video) files. The windows media player is a very powerful media tool that was designed

by Microsoft and is shipped in with all of their operating systems. In fact it is the default media player for

all windows operating systems.

To begin with, let us open the media player by left clicking on the icon. By default you can locate this icon

in the start menu.

http://www.ask.com/wiki/Writing?qsrc=3044http://www.ask.com/wiki/Sound?qsrc=3044http://www.ask.com/wiki/Image?qsrc=3044http://www.ask.com/wiki/Animation?qsrc=3044http://www.ask.com/wiki/Footage?qsrc=3044http://www.ask.com/wiki/Interactivity?qsrc=3044

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Doing this opens up one of the two windows medial player views, either the now playing view;

Or the library view.

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The now playing view is used to show the current files that have been loaded and are currently being

played. In the library view you have access to the various storage locations on the computer as well as

various categories of multimedia data that can be found on them. To toggle between the views you would

simply have to left click on the toggle view in either of the windows. This buttons look something like;

or

As stated before the windows media player is used to play audio and video files. To play an audio or a

video file you can follow any of the following procedures.

Drag and drop the audio/video file into the now playing window and press play

Drag and drop the files to be played into the portion of the library window where you have the

Drag items here to create a playlist text.

Please note that even though we drag and drop the actual media files in the media player. We do not

actually move them from their storage locations. What we do is pass a shortcut string to the media

player. The player uses this shortcut strings as a path to locate the media files where ever they are really

stored and plays them from there. These shortcuts can then be organized and played in a predefined

pattern. A collection of such shortcuts is referred to as a playlist.

Now let us have a look at the player controls.

The player controls consist of a set of standardized buttons that are displayed on the screen and used to

control the playback of media files. These controls are;

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Shuffle on/off; this button is used to turn the shuffle on(files are played in a random manner) or

off (files are played in the order in which they appear in the playlist.

Repeat on/off; this button is used to determine if the playlist or single media file should be played

just once or over and over again.

Stop; this button is used to stop playback

Previous; if this button is clicked once during playback, it starts playing the current file from the

beginning. If it is clicked on twice then it plays the media file that is found right before the file that

is currently playing.

Play; this button is used to either pause or resume playback

Next; this button is used to skip to the next file in the playlist. If the mouse button is held down on

this key, it forwards the file.

Mute; the mute button is used to completely eliminate all the audio output of the file that was

currently playing.

Volume; the volume slide bar is used to either increase or decrease the volume.

Another very useful feature of the windows media player is its ability to synchronize the playlists in the

library with any portable storage device. This feature can be accessed through the media library view and

is in the form of a tab with a Sync label. When an external storage device is connected to the computer,

aside being visible in the windows explorer, it is also shown in the media player under the Sync tab. To

copy media files to that device all you have to do is to click on the sync tab and drag the media items that

you want to synchronize then to complete the process you have to click on the start sync button.

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This feature becomes very useful when we want transfer media files onto portable media players.

The media player can also be used to burn media files to discs. Burning is a term that is used to refer to

the process of permanently saving files to optical discs. To access this feature, click on the burn tab. Then

drag the media files to the burn list and click on the start burn thumbnail.

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FILE EXTENSIONS AND CODECS

Another very important issue that deserves some attention is the encoding of media files. Just as every

software component of the computer media files are simply strings of 0s and 1s. These strings are

arranged in specific patterns. Before the media player can play back the multimedia content of the file it

has to be able to know the formula for the arrangement. The process through which the media player

converts these strings of 0s and 1s into comprehensible media material is called decoding. The tool that

the media player uses to perform the decoding is called a codec. Without the codec or plug-in for a

particular media format, the player will not be able to play that media file. Currently there are many

codecs available in the software market and these can be downloaded and installed to increase the

compatibility of the media player. Media formats can be easily identified by the three letter suffix that

accompanies the file name. Examples of these include; .wma, .wmv, .mp3, .avi, . . .

WINDOWS EXPLORER AND THE USE OF REMOVABE STORAGE DEVICES

The windows explorer is a file manager application that comes with the Microsoft office operating system

and was first introduced with the Windows 95 version of the OS. It provides a GUI that can be used to

assess the file system; it is also the component of windows that presents some of the user interfaces such

as the desktop icons, the start menu, the taskbar, and the control panel. Collectively, these features are

known as the windows shell.

To access the windows explorer you would have to click on the start button and then go to the

accessories file. The windows explorer can then be opened by clicking on the icon.

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The image above the home screen of the windows explorer. This window is split into two. The left portion

of it is used to show the file system of the entire computer, including any external storage devices. The

right collection shows the files and folders that can be found in the selected storage location on the right.

For example in the window above the files, folders and icons shown in the left portion of the window are

all found on the desktop.

You can use the windows explorer to add and delete files and folders. To add a file or a folder simply right

clicks on an empty space in the right window and from the drop down menu select new. Then select

folder by clicking on it.

As soon as your new file/folder is created you would be asked to enter a name for it n the text box below

the folder icon. Push the enter or return key to save the changes. In a case where you made a mistake

whilst entering the file name, it is actually possible to change it. To change the file name, select the file by

clicking on it and then right click on it to reveal the drop down menu. In the menu select the rename

option. Edit the file name and push the enter key to save changes.

NB: a folder is a collection of files.

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VIRUSES

INTRODUCTION

A computer virus like any other application is a computer program. But unlike other applications

computer viruses do not perform any task that is of benefit to the user, instead they are harmful

programs that interfere with the normal functioning of other useful programs. At this point I would

expect you to be wondering. Why create programs that would interfere with the proper operation of

other useful programs. The answer is simple; to cause damage, the reasons however may be diverse.

Some viruses are created by newbie programmers that want to make a name for themselves, other

viruses are created as a result of a strategic attack on corporate data, again viruses have been created to

destroy the market demand for monopolistic software applications and hardware components.

In 1949 Hungarian American mathematician John von Neumann, at the Institute for Advanced Study in

Princeton, New Jersey, proposed that it was theoretically possible for a computer program to replicate. This

theory was tested in the 1950s at Bell Laboratories when a game called Core Wars was developed, in which

players created tiny computer programs that attacked, erased, and tried to propagate on an opponent's

system.

In 1983 American electrical engineer Fred Cohen, at the time a graduate student, coined the term virus to

describe a self-replicating computer program. In 1985 the first Trojan horses appeared, posing as a

graphics-enhancing program called EGABTR and as a game called NUKE-LA. A host of increasingly

complex viruses followed.

The so-called Brain virus appeared in 1986 and spread worldwide by 1987. In 1988 two new viruses

appeared: Stone, the first bootstrap-sector virus, and the Internet worm, which crossed the United States

overnight via computer network. The Dark Avenger virus, the first fast infector, appeared in 1989,

followed by the first polymorphic virus in 1990.

Computer viruses grew more sophisticated in the 1990s. In 1995 the first macro language virus, WinWord

Concept, was created. In 1999 the Melissa macro virus, spread by e-mail, disabled e-mail servers around

the world for several hours, and in some cases several days. Regarded by some as the most prolific virus

ever, Melissa cost corporations millions of dollars due to computer downtime and lost productivity.

The VBS_LOVELETTER script virus, also known as the Love Bug and the ILOVEYOU virus, unseated

Melissa as the world's most prevalent and costly virus when it struck in May 2000. By the time the

outbreak was finally brought under control, losses were estimated at U.S.$10 billion, and the Love Bug is

said to have infected 1 in every 5 PCs worldwide.

The year 2003 was a particularly bad year for computer viruses and worms. First, the Blaster worm

infected more than 10 million machines worldwide by exploiting a flaw in Microsofts Windows operating

system. A machine that lacked the appropriate patch could be infected simply by connecting to the Internet.

Then, the SoBig worm infected millions more machines in an attempt to convert systems into networking

relays capable of sending massive amounts of junk e-mail known as spam. SoBig spread via e-mail, and

before the outbreak was 24 hours old, MessageLabs, a popular e-mail filtering company, captured more

than a million SoBig messages and called it the fastest-spreading virus in history. In January 2004,

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however, the MyDoom virus set a new record, spreading even faster than SoBig, and, by most accounts,

causing even more damage.

TYPES OF VIRUSES

There are many categories of viruses, including parasitic or file viruses, bootstrap-sector, multipartite,

macro, and script viruses. Then there are so-called computer worms, which have become particularly

prevalent. A computer worm is a type of virus. However, instead of infecting files or operating systems, a

worm replicates from computer to computer by spreading entire copies of itself.

Parasitic or file viruses infect executable files or programs in the computer. These files are often identified

by the extension .exe in the name of the computer file. File viruses leave the contents of the host program

unchanged but attach to the host in such a way that the virus code is run first. These viruses can be either

direct-action or resident. A direct-action virus selects one or more programs to infect each time it is

executed. A resident virus hides in the computer's memory and infects a particular program when that

program is executed.

Bootstrap-sector viruses reside on the first portion of the hard disk or floppy disk, known as the boot sector.

These viruses replace either the programs that store information about the disk's contents or the programs

that start the computer. Typically, these viruses spread by means of the physical exchange of floppy disks.

Multipartite viruses combine the abilities of the parasitic and the bootstrap-sector viruses, and so are able to

infect either files or boot sectors. These types of viruses can spread if a computer user boots from an

infected diskette or accesses infected files.

Other viruses infect programs that contain powerful macro languages (programming languages that let the

user create new features and utilities). These viruses, called macro viruses, are written in macro languages

and automatically execute when the legitimate program is opened.

Script viruses are written in script programming languages, such as VBScript (Visual Basic Script) and

JavaScript. These script languages can be seen as a special kind of macro language and are even more

powerful because most are closely related to the operating system environment. The 'ILOVEYOU' virus,

which appeared in 2000 and infected an estimated 1 in 5 personal computers, is a famous example of a

script virus.

Strictly speaking, a computer virus is always a program that attaches itself to some other program. But

computer virus has become a blanket term that also refers to computer worms. A worm operates entirely on

its own, without ever attaching itself to another program. Typically, a worm spreads over e-mail and

through other ways that computers exchange information over a network. In this way, a worm not only

wreaks havoc on machines, but also clogs network connections and slows network traffic, so that it takes

an excessively long time to load a Web page or send an e-mail.

however not all programs that interfere with the normal functioning of other computer programs are

viruses. Some of these are described below.

There are other harmful computer programs that can be part of a virus but are not considered viruses

because they do not have the ability to replicate. These programs fall into three categories: Trojan horses,

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logic bombs, and deliberately harmful or malicious software programs that run within a Web browser, an

application program such as Internet Explorer and Netscape that displays Web sites.

A Trojan horse is a program that pretends to be something else. A Trojan horse may appear to be

something interesting and harmless, such as a game, but when it runs it may have harmful effects. The term

comes from the classic Greek story of the Trojan horse found in Homers Iliad.

A logic bomb infects a computers memory, but unlike a virus, it does not replicate itself. A logic bomb

delivers its instructions when it is triggered by a specific condition, such as when a particular date or time

is reached or when a combination of letters is typed on a keyboard. A logic bomb has the ability to erase a

hard drive or delete certain files.

Malicious software programs that run within a Web browser often appear in Java applets and ActiveX

controls. Although these applets and controls improve the usefulness of Web sites, they also increase a

vandals ability to interfere with unprotected systems. Because those controls and applets require that

certain components be downloaded to a users personal computer (PC), activating an applet or control

might actually download malicious code.

VIRAL CURE, PREVENTION AND DATA PROTECTION

Computer users can prepare for a viral infection by creating backups of legitimate original software and

data files regularly so that the computer system can be restored if necessary. Viral infection can be

prevented by obtaining software from legitimate sources or by using a quarantined computerthat is, a

computer not connected to any networkto test new software. Plus, users should regularly install

operating system (OS) patches, software updates that mend the sort of flaws, or holes, in the OS often

exploited by viruses. Patches can be downloaded from the Web site of the operating systems developer.

However, the best prevention may be the installation of current and well-designed antiviral software.

Such software can prevent a viral infection and thereby help stop its spread.

Several types of antiviral software can be used to detect the presence of a virus. Scanning software can

recognize the characteristics of a virus's computer code and look for these characteristics in the computer's

files. Because new viruses must be analyzed as they appear, scanning software must be updated

periodically to be effective. Other scanners search for common features of viral programs and are usually

less reliable. Most antiviral software uses both on-demand and on-access scanners. On-demand scanners

are launched only when the user activates them. On-access scanners, on the other hand, are constantly

monitoring the computer for viruses but are always in the background and are not visible to the user. The

on-access scanners are seen as the proactive part of an antivirus package and the on-demand scanners are

seen as reactive. On-demand scanners usually detect a virus only after the infection has occurred and that is

why they are considered reactive.

Antivirus software is usually sold as packages containing many different software programs that are

independent of one another and perform different functions. When installed or packaged together, antiviral

packages provide complete protection against viruses. Within most antiviral packages, several methods are

used to detect viruses. Check summing, for example, uses mathematical calculations to compare the state

of executable programs before and after they are run. If the checksum has not changed, then the system is

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uninfected. Check summing software can detect an infection only after it has occurred, however. As this

technology is dated and some viruses can evade it, check summing is rarely used today.

Most antivirus packages also use heuristics (problem-solving by trial and error) to detect new viruses. This

technology observes a programs behavior and evaluates how closely it resembles a virus. It relies on

experience with previous viruses to predict the likelihood that a suspicious file is an as-yet unidentified or

unclassified new virus.

Other types of antiviral software include monitoring software and integrity-shell software. Monitoring

software is different from scanning software. It detects illegal or potentially damaging viral activities such

as overwriting computer files or reformatting the computer's hard drive. Integrity-shell software establishes

layers through which any command to run a program must pass. Check summing is performed

automatically within the integrity shell, and infected programs, if detected, are not allowed to run.