Embed Size (px)
Citation preview
The Internet & the World Wide Web
Chapter 2
Exploring Cyberspace
Chapter 2: Key Questions
2.1 What are the means of connecting to the Internet, and how fast are they?
2.2 What are the three types of Internet service provider, and what kinds of service do they provide?
2.3 What are the components of an e-mail address, and what are netiquette and spam?
2.4 What are Web sites, Web pages, browsers, URLs, and search engines?
2.5 What are FTP, Telnet, newsgroups, real-time chat, and e-commerce?
To Access the Internet, You Need…
An access device A physical connection An Internet Service Provider (ISP)
Can you give examples of each?
Physical Connection
Telephone (dial-up) modem Several high-speed phone lines
– ISDN– DSL– T1
Cable modem Wireless
Data Transmission Speeds
Upload – data from local computer to remote Download – data from remote to local Bandwidth
– Data that is sent through a communications channel in a given amount of time
Data transmission speeds:– Bps – bits per second– Kbps – kilobits per second– Mbps – megabits per second– Gbps – gigabits per second
8 bits = 1 byte = 1 character
Telephone Modem
See panel 2.3 on page 39
High Speed Phone Lines
ISDN (Integrated Services Digital Network)– Hardware & software– Uses traditional telephone lines (128 Kbps)
DSL (digital subscriber line)– Always on– Transmission rate is consistent (1.5-8.4 Mbps)– Must live within 3.3 miles of a phone company switching office
T1 line (1.5 Mbps)– Used by corporate, government, and academic sites
Cable Modems
Connects a PC to a cable-TV system that offers Internet access
Always on Competes with DSL Transmission rate may not be consistent
during peak hours Speed:10 Mbps
Wireless Systems
Communications satellite– Radio waves (microwaves) transmitted from earth-
based stations– Receives data at 400 Kbps & sends data at 56 Kbps
(with phone line)
Other wireless connections– Radio waves for cellular phones– Sends data up to 155 Mbps
Three Types of ISP Services
Free-service providers– NetZero, AltaVista, BlueLight.com– Advertisements and personal info
Basic-service providers– Offer local connection
Full-service providers– AOL, Earthlink, MSN– More technical support and international access
How to Get E-mail Software?
Purchase– MS Outlook express, Lotus Notes
Get as a part of other package– Netscape Communicator
Provided by your ISP– AOL
Free Email Services– Yahoo, Hotmail
E-mail Addresses
User ID Domain Name
Domain Top-level domain Country
(location) (domain type)
Attachments – Attached to emails– Formatting preserved– Recipient must have software to read them
Instant messaging– Cross between e-mail and phone– Message pops up instantly on the screen if user is
logged on
Netiquette
Use FAQs Avoid flaming Don’t shout Avoid sloppiness Make attachments small
Quote only relevant portion when replying
Avoid spams
World Wide Web
Uses of the WWW– E-mail– Entertainment– E-commerce
E-tailing, auction, online finance, on-line job hunting, B2B
Why the WWW is inviting & easy to use– Multimedia format : graphics, video, audio, text– Use of hypertext
Web Terms
Web site– a computer with a domain name is called a site
Web pages– a document that can include text, pictures, sound, and video
Browsers– software that enables users to view Web pages URLs
URLs (Universal Resource Locator) – a string of characters that point to a specific Web page
Web portals– Web sites that group together popular features
Web Terms
Multimedia format– graphics, video, audio, text
HTML (hypertext markup language)– A language used to specify document structure,
formatting, and links to other documents
HTTP – hypertext transfer protocol –rules that allow
browsers to connect with Web servers
Search Engine Types
Human-organized search sites– subject experts (humans) do the indexing– Yahoo!. AOL, MSN, Netscape, Lycos
Computer-created search sites– software "spiders" (software) do the indexing– Northern Light, Excite, WebCrawler, FAST Search, Inktomi
Hybrid search sties– humans supplemented by computer indexes– AskJeeves, Direct Hit, Go, GoTo.com, Google, HotBot, Snap
Metasearch sites– sends query to other search tools and compile the results– Go2Net/MetaCrawler, SavvySearch, Dogpile, Inference
Multimedia on the Web
Plug-ins & helper applications Multimedia development
– Applets, Java, JavaScript, ActiveX
Text and images Animation Video Audio
More Internet Resources
FTP – File Transfer Protocol– a program that can transfer files to one compute to another
Telnet– a program that allows you to connect to remote computers on
the Internet Newsgroups
– a giant electronic bulletin board on which users conduct written discussions about a specific subject
Real-time chat– participants have a typed discussion while online at the same
time
