What is a network: local and global
A computer network lets devices exchange data and share resources. You will learn how local (LAN) and global (WAN) networks differ and how the internet is built.
All topics (1 of 11)
Chapter 1. Computer networks
Chapter 2. Information security
Chapter 3. Creating web pages
A computer network is a set of devices (computers, phones, printers, servers) connected to exchange data. A network makes it possible to send files, share a printer and reach the internet. Devices connect by cable (for example, Ethernet) or by radio waves (Wi-Fi).
A network has several main parts. Every computer has a network card; a switch connects devices inside one network, while a router links different networks together. Data travels in small pieces called packets, and the rules of transfer are defined by protocols (for example, TCP/IP).
A local area network (LAN) connects devices in one room, school or building: it is fast and usually belongs to a single organization. A wide area network (WAN) links cities and countries and is usually built by telecom operators. The internet is the largest global network in the world, a union of countless local and wide area networks.
A home Wi-Fi router does two jobs: it connects phones and laptops to the home network (LAN) and links that network to the internet (WAN) through the provider. So home devices talk to each other inside their own network, and to websites on the internet through the router.
Key takeaways
- A computer network is a set of devices connected to exchange data.
- A switch connects devices inside one network, while a router links different networks.
- Data is split into packets and sent according to protocol rules (for example, TCP/IP).
- A LAN covers a small area and a WAN a large one; the internet is a global network.
Practice tasks
- Draw a diagram of the school computer lab network: show the computers, the switch, the router and the path to the internet.
- List all network devices in your home and note in a table whether each one connects by cable or by Wi-Fi.
- Classify the following as a local (LAN) or global (WAN) network and explain why: a school computer lab, a network linking a bank’s branches in different regions, home Wi-Fi, the internet worldwide.
Review questions
Test yourself: think first, then reveal the answer.
1How do the jobs of a switch and a router differ?Show answerHide answer
A switch connects devices inside one network, while a router links different networks (for example, a home network and the internet).2Why is the internet called a “network of networks”?Show answerHide answer
Because it is formed by connecting many independent networks: local, corporate and provider networks.3What is a protocol?Show answerHide answer
A set of rules that devices follow when exchanging data (for example, TCP/IP).
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