FAQ is an acronym for Frequently Asked Questions. It is usually pronounced as a word, fack, although some "spell-pronounce" it as eff aye kew.
The FAQ is an Internet tradition originating from periodic summary messages posted to USENET news groups in an attempt to reduce the continual reposting of the same basic questions. (just speculating)
Wikipedia has its own FAQ at Wikipedia FAQ, and there are thousands more available; to assist in locating them, several sites catalog them and provide search capabilities -- for example, the Internet FAQ Consortium.