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Computer-science_A-level_Cie

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  30. circuit-switching-packet-switching
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  44. networks-and-the-internet
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Internet vs WWW

What is the Internet?

  • The Internet is a global network of networks (Interconnected Network)

  • The Internet is the most well-known Wide Area Network (WAN)

  • The Internet is the infrastructure used to provide connectivity to the World Wide Web (WWW)

  • Uses protocols like TCP/IP to transfer data between devices and networks

What is the World Wide Web (WWW)?

  • The world wide web, or simply the web, is a collection of websites and web pages that are accessed using the Internet

  • It was created in 1989 by Tim Berners-Lee, who envisioned it as a way to share and access information on a global scale

  • The web consists of interconnected documents and multimedia files that are stored on web servers around the world

  • Web pages are accessed using a web browser, which communicates with web servers to retrieve and display the content

  • Uses protocols like HTTP and HTTPS to request and deliver web content

Internet hardware

Modem

  • Modem stands for modulator-demodulator

  • Converts digital signals from a computer into analogue signals to send over telephone or cable lines

  • Also converts analogue signals back into digital so the computer can understand them

  • Allows devices to connect to the internet through technologies like:

    • DSL

    • Cable

    • Dial-up

  • Used to send and receive data over long distances via traditional communication lines

Public Switched Telephone Network (PSTN)

  • Developed soon after the invention of the telephone in the late 1800s

  • Originally built to handle voice communication over copper wires

  • As the demand for other forms of communication grew, the PSTN was adapted to enable internet access

  • Used to connect computers/devices and LANs between towns and cities

  • Traditional copper telephone lines are being slowly replaced with fibre optic cables

    • Fibre gives access to higher bandwidth and faster data transfer speeds

Dedicated lines

  • Dedicated lines (e.g. T1, T3, and fibre-optic) provide exclusive, high-speed connections between two points

  • Unlike the PSTN, these connections are always active and not shared with other users

    • Faster and more reliable

    • Ideal for businesses and organisations needing consistent, high-bandwidth internet

    • Better for activities like video conferencing, cloud computing, and large file transfers

Connection type

Speed

T1 Line

Up to 1.54 Mbps

T3 Line

Up to 45 Mbps

Fibre-Optic

Speeds in the gigabits

Cellular networks

  • Provide wireless communication for mobile phones and other portable devices

  • The network is made up of cells, each served by a cell tower (base station)

  • Devices connect to the nearest tower to send and receive signals

  • As a user moves, their device automatically switches to the next closest tower (handover)

  • Used for voice calls, text messaging, and mobile data (internet access)

  • Support different generations of mobile technology:

    • 2G – Basic calls and texts

    • 3G – Mobile internet and video calling

    • 4G – Fast internet browsing and streaming

    • 5G – Very high-speed internet, low latency (great for gaming and real-time apps)

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