I would like to add (simply reading Silly’s post), that the forum automatically keeps a public record of the edits made to a post unless the entire post is deleted, in which case it is kept only for 24 hours. However, most of us don’t want to dig around in the history to see what was said before, so it is simply more convenient and considerate to write: EDIT yourself!
Reddit helps to remember that, too…
I do just browse reddit too much, though…