the subject name says it all.

A sticky is a topic in one of the forums that always stays at the top of the page. It becomes a sticky if a member of the Scratch Team thinks it should be one.

A “sticky” is a post that is shown at the top of each forum, despite having other posts that are more recent than it. Stickies are the important topics that the ST wants you to see.

A sticky is a topic that is important that stays at the top of the page. Only Scratch Team members can make topics stickies and they can also remove stickies.