Any post to a thread will cause the thread to show activity and thus appear at the top of the "New Posts" display. Sometimes a poster's intent is to simply bring the thread to everyone's attention once again. I believe TOTV is set up to not allow a null/empty post - thus you'll see some use the acronym "bump" (generally recognized as standing for Bring Up My Post) or simply three periods (...) as the sole content of the post.
Bill
