Introduction to ICT and Programming

Lecture # 3 : Internet & World Wide Web

The World of The Internet

The Internet & the World Wide Web

2.1 Choosing Your Internet Access Device & Physical Connection: The Quest for Broadband

2.2 Choosing Your Internet Service Provider (ISP)

2.3 Sending & Receiving E-Mail

2.4 The World Wide Web

2.5 The Online Gold Mine: More Internet Resources, Your Personal Cyberspace, E-Commerce, & the E-conomy

Exploring Cyberspace

2.1 Choosing Your Internet Access

This section discusses the different technologies used to connect individuals to the internet including: – 1. Access device: a personal computer

with a modem – 2. Physical connection: a telephone

line

Device & Physical Connection

Physical connection

The wired or wireless means of connecting to the Internet.

Data Transmission Rates

Data is transmitted in bits per second. – bps stands for bits per second. A bit is the smallest unit

of information used by computers. A computer with an older modem might have a speed of 28,800 bps per second.

– Kbps stands for kilobits per second. This is the most frequently used measure.

– Mbps stands for megabits per second

– Gbps stands for gigabits per second

Bandwidth

- an expression of how much data can be sent through a communications channel in a given amount of time

Broadband - very high speed connection

Download & Upload

Download - to transmit data from a remote computer to a local computer

Upload - to transmit data from a local computer to a remote computer

Telephone (Dial-Up) Modem:

Modem - device that sends and receives data over telephone lines to and from computers

Most modems today have a maximum speed of 56 Kbps.

Low Speed but Inexpensive & Widely Available

Using a modem and phone line to establish a connection to the Internet is called making a dial-up connection.

High-Speed Phone Lines:

Integrated Services Digital network (ISDN) - hardware and software that allows voice, video, and data to be communicated over traditional copper-wire telephone lines. Speeds up to 128 kbps.

Digital Subscriber Line (DSL) - also uses regular phone lines but much faster than ISDN. Download speeds 1.5 – 8.4 Mbps

T1 - a traditional trunk line that carries 24 normal telephone circuits and has a transmission rate of 1.5 Mbps

More Expensive but Available in Most Cities

High-Speed Lines

Cable : Close Competitor to DSLSpeeds up to 10 Mbps

Fiber Optics: Can support speeds up to 2 Gbps

Wireless Systems: Satellite & Other

Satellite: With a pizza-size satellite dish on your roof, you can receive data at the rate of 400 Kbps from a communications satellite, a space station that transmits radio waves called microwaves from earth-based stations.

Other wireless connections: In urban areas, some businesses are using radio waves transmitted between towers that handle cellular phone calls, which can send data at up to 155 Mbps.

Through-the-Air Connections

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