A sticky post is paid feature that allows authors to stick their post at the top of their tribemates Tribal Stream.
Normally a Tribal Stream is sorted by time, with the newest posts on top. If your tribemates logs in hours or days after your post was published, it's likely that your tribemates may not see it, because it's buried beneath newer posts.
By making your post sticky, your post will stay at the top of your Tribemates streams until they share or hide it, or until the posts 5 day lifespan is up.
Sticky posts are a one time, $5 cost, and can be purchased from any page that contains an active post.
You can promote your own posts as well as others.