What is a network?

A computer network is two or more devices connected together so that they can communicate and share data or resources. The connection could be a cable, a wireless link or a mixture of both. What makes it a network is that the devices can pass information to each other instead of each one working completely alone.

For example, a phone and a laptop in the same house could be joined by a wireless link. Once they are connected, a photo taken on the phone can be opened on the laptop within seconds, and either device can send a file to a friend. Before they were connected, each device could only use what was stored on it or plugged directly into it.

A stand-alone computer is a computer that is not connected to a network or to the internet. It runs on its own, so it cannot directly share data or resources with other devices: nothing it stores is available to another machine over a connection, and it cannot use another machine's hardware. A stand-alone computer is not completely cut off from the outside world, though, because you can still move a file onto it using a USB flash drive. That is copying by hand, not networking, because there is no connection between the devices.

Two devices are already enough to make a network, so the word does not only describe big systems covering many rooms or buildings. What matters is that the devices are connected and that the connection lets them communicate or share something.