In the language of message boards, a “sticky” is a thread that is set to always appear at the top of the front page. Look at the top of the topic lists.
[sticky] threads can be editable. The [sticky] threads currently on the main CR page are also [closed]. Their were threads that were [sticky] but not [closed] (ex. the nightly Dvar Torah thread).
This thread needs real content for it to become [sticky]. And by the way, most people don’t notice [sticky] threads.