An extension to 802.11 specification developed by the IEEE for wireless LAN (WLAN) technology. 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The 802.11a specification uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS and provides up to 54 Mbps in the 5GHz band.
See 802.11 for a complete overview of the 802.11x family of specifications.
Also see the "Wireless LAN Standards chart" in the Quick Reference section of Webopedia.
See also "How Wireless Networks Work" in the Did You Know... section of Webopedia.