hehe I'm answering all the questions like the know-it-all I am . Sorry Paul
I think it tells based on the times you log on and off. Like, all the posts that are made after the time you logged off would be considered new posts, etc., etc., etc., and so forth. Hope that helps. 8)
Thanks Hermione - no need at all to apologise for helping.
I really like clicking on the <img src="/forum/templates/subSilver/images/icon_newest_reply.gif"> indicator which takes you straight to any messages posted on a particular thread since last time you were online.