Wi-Fi is a technology that enables PCs and other devices to connect to the internet without the need for a physical connection to a phone-line or other device. It works by sending information via radio waves.
For the last three years practically all laptop computers have been sold with the capability to connect to Wi-Fi networks. Increasingly, mobile phones and, to a lesser extent, digital music players and other consumer electronic devices, have Wi-Fi built in.
A Wi-Fi-enabled device connects wirelessly to a base station, which in turn has a high-speed connection to the internet. Unlike mobile phone technology, Wi-Fi base stations are about the size of a paperback novel.
In an outdoor setting each station can provide coverage up to about 90 metres away. The area of coverage is known as a "hotspot".
Many hotels and cafes provide indoor hotspots. Increasingly, public authorities around the world are following suit.