This is meant for questions which are generalized forms of questions which get asked frequently. See tag details for more information.
When you add a question marked faq, please also update the list of questions: List of Generalizations of Common Questions.
The question which prompted this: Coping with *abstract* duplicate questions.
Note: Even though one might argue that tagging a question as faq should be enough, and there is no need to update the above list, updating the above list will serve to bring this policy back to attention and help raise awareness periodically.