The term used to describe the family of 802.11 specifications developed by the IEEE for wireless LAN technology. 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients.
Recommended Reading: See 802.11 for a complete overview of the 802.11x family of specifications.
Also see Webopedia’s Wireless LAN Standards chart and How Wireless Networks Work.