A hashtag is a type of label or metadata tag used on social network and microblogging services which makes it easier for users to find messages with a specific theme or content.
I know that. It’s a kind usurper of a term. An exclamation point is an exclamation point and a question mark is a question mark. I don’t know of any other terms for those two, but I have used the term “splat” when referring to an asterisk.