"FAQ" stands for "Frequently Asked Questions". FAQ can refer to the list of questions itself (a FAQ) or to the questions individually (FAQ).
A FAQ is designed to help people find answers to things they don't understand. Usually, FAQs are online documents with hyperlinks.
A well-done FAQ list will organize the questions into categories or groups. Usually, the questions are written near each other, with links to their answers. This allows the reader to quickly search through the questions to see if his question is listed.
Click to view a few different FAQ pages:
U.S. Copyright FAQ
Sesame Street's My Street FAQ