hashtags allow the user to describe to the machine how to categorize a piece of text. So, for example, "I just stepped in shit. #winning" is a way for a user to have the sentence "I just stepped in shit" categorized in a specific way; not necessarily the way the machine would have chosen to categorize it. You're not supposed to just hashtag every word. Optimally, if another human clicks on one of your hashtags, they get to see some thematically related content. On some networks, though (Instagram in particular), hashtags are used to game the system; since there are discovery featured built around hashtags, merely including a popular hashtag can improve your visibility. So self-indulgent teens will hashtag their selfies with #food, because it's a primitive form of SEO gaming, and they wind up getting more likes. Or like with Go, people who code Go never actually call it "golang", but #golang is the canonical hashtag because it's more specific than #go, which is ... noise.