This is kind of confusing
to explain, but -
is found at the top of a group of threads in a forum and always stays at the top. They contain important information.
For example, at the top of the forum page Newbies/introductions, there are 5 Sticky's - Acronyms/Abbreviations/Definitions, Start Here, Poll, Useful Curly Links, and FAQ. These threads will always stay at the top of that forum, for easy access.
Hope that helps!!