Wi-Fi - Definition from the Hotspot Shield Glossary
While the term Wi-Fi doesn’t actually stand for anything, Wi-Fi is concerned with the IEEE 11.b 802 standards that are used for WLAN’s or Wireless Local Area Networks. Effectively Wi-Fi is wireless networking - creating a network with the physical need for cables and wires.
Wi-Fi can be used to create networks within a household or an office for example - The means of connection to the internet i.e. a modem will have a built in Wireless transmitter, and each device in the network will have wireless receivers allowing them to connect to the Wi-Fi network using a set username and password. Wi-Fi is implemented using radio waves much like a radio station - The Wi-Fi transmitter will broadcast these waves and any device with the correct authentication that can receive those waves will be able to gain access to the wireless network.