Your phone alone is not much use
Turn off your Wi-Fi and your mobile data. Now try to use your group chat, a video call or a map. They do not work.
Most of what a phone does needs a network. A network is two or more devices joined together so that they can share data. Today you find out why we build networks, and what kinds there are.
Key words
| Word | What it means | Example |
|---|---|---|
| Network | Two or more devices joined together to share data. | The college Wi-Fi |
| PAN | Personal area network. Your own devices, close to you. | Phone and wireless earbuds |
| LAN | Local area network. One building or site. | A college network |
| MAN | Metropolitan area network. A town or city. | A city council joins all its libraries |
| WAN | Wide area network. Many towns or countries. | The internet |
| VPN | Virtual private network. A private link across a public network. | Working from home |
| Ethernet | A common way to join computers in a building, usually with a copper cable. | The cable behind a desk PC |
| Encryption | Scrambling data so that only the right people can read it. | A secret code |
| Malware | Bad software made to harm a computer or steal data. | A virus |
| Media | What carries the signal: a cable, light or radio waves. | Copper, fibre, Wi-Fi |
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Benefits and drawbacks
| Benefits | Drawbacks |
|---|---|
| Share files, printers and an internet connection | Malware can spread from one device to all the others |
| Talk to each other: email, chat, video | Building and repairing it costs money and needs skilled people |
| Save work in one place and back it up | If the network fails, everyone is stopped |
| Control accounts and updates from one place | More people can try to get in, so you need better security |
| Share the cost of expensive equipment | A busy network can be slow |
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Quick check: benefit or drawback?
Have a go
Quick check: benefit or drawback?
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Four sizes of network
We describe a network by how far it reaches and how many people use it.
A PAN is around one person, about 10 metres. A LAN covers one building. A MAN covers a town or a city. A WAN covers a very large area, even the whole world. The internet is the biggest WAN.
The types compared
| Type | Users | Connection media | Coverage | Example |
|---|---|---|---|---|
| PAN | One person | Bluetooth, a USB cable | About 10 metres | Phone and smartwatch |
| LAN | From 10 to thousands | Ethernet cable, Wi-Fi | One building or site | A college |
| MAN | Many organisations | Fibre cable, radio links | A town or a city | Traffic cameras in a city |
| WAN | Very many, even billions | Fibre, undersea cables, satellites | Countries and continents | The internet |
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A VPN: a private tunnel
A VPN is not a size. It is a private connection built on top of a public network such as the internet.
The data goes into a "tunnel". Encryption scrambles it, so other people cannot read it on its way. A worker at home can use a VPN to reach the office network as if they were in the building. Two offices can also join their networks with a VPN.