Wi-Fi has become very popular because once you have a base station, any number of desktop or laptop computers can be connected to your broadband service without the need for any cables or installing extra phone lines.

So if you have a second computer in an upstairs room, or a laptop as well as a desktop, the same broadband service will be available on all your machines at the same time.

You can even use your laptop in the garden!

SOURCE  http://www.bbc.co.uk