@pancake I swear this is not meant as a "well actually" but I think it's an important distinction to make: Twitter did not invent hashtags. We, their users, did. Twitter had a very simple word-based search, so searching for stuff was hard unless it was a single word everyone agreed on, so somebody started doing #thisthing and it went viral as a solution. Same thing happened for retweet. It wasn't a feature. Users copy-pasted tweets and adopted the convention "RT @name" to give credit.