A thread is contained in a forum and may have an associated date that is taken as the date of the last post (options to order threads by other criteria are generally available). When a member posts in a thread, it will jump to the top since it is the latest updated thread. Similarly, other threads will jump in front of it when they receive posts. When a member posts in a thread for no reason but to have it go to the top, it is referred to as a bump or bumping. It has been suggested that “bump” is an acronym of “bring up my post”; however, this is almost certainly a backronym, and the usage is entirely consistent with the verb “bump” which means “to knock to a new position”.