# What does the exclamation mark on a timestamp mean?

I've noticed a couple of times that in comments (where I've seen it, but maybe it's in questions/answers as well) that sometimes the stamp is -- UserName X [time unit(s)] ago !

Actually, you're probably referring to the edit indicator, which looks like a pencil. If you hover over it it will say this comment was edited. If it's been edited multiple times it will also state that.