Wi-Fi (Wireless Fidelity) : Wi-Fi is the popular term for a high-frequency wireless local area network (WLAN). Wi-Fi is specified in the 802.11b specification from the Institute of Electrical and Electronics Engineers (IEEE) and is part of a series of wireless specifications together with 802.11, 802.11a, and 802.11g. All four standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing. The 802.11b (Wi-Fi) technology operates in the 2.4 GHz range offering data speeds up to 11 megabits per second.
From : http://www.mcsx.co.uk/glossary.php