I keep seeing the word 'bump' in bulletin board posts. What's that all about?

Well, when someone posts a question and it receives no replies, it gradually falls to the bottom of the pile and eventually drops off the first page where no one can see it. Instead of giving up and letting the thread die gracefully, some people reply to their own post to bring it back up to the top of the forum in the hope that it will get a better response the second time round. You could type anything in your reply and it would have the same effect, but 'bump' seems most appropriate because it elevates the thread to the top of the forum.