Interesting librarian lore: The way tumblr’s tagging system works actually has a name! It’s called a folksonomy, based on the word taxonomy, i.e. creating systems to classify information so we can fucking…find it later. The reason it has the prefix folk- is because it is created “by the people (who use the system)” and not contained by something called a “controlled vocabulary” where you have to fit whatever your tagging into per-defined tags.
Three clear examples from fandom-land I can give to demonstrate different tagging systems:
Controlled Vocabulary: Fanfiction.net uses a (really terrible) controlled vocabulary. Whoever’s responsible for the CV does not change it often and it’s hard to fit content into the containers, and users have no creativity or control.
Folksonomy: Tumblr. You can say whatever tf you want in the tags! Which is very cool and makes for whole new ways of engaging! The drawback is that it’s frankly AWFUL for finding content. If you tag #star wars and your friend tags #SW they will not show up and there is no one combining those tags.
Hybrid: Ao3. Say what you want about Ao3, we have it made in the fucking shade over there. You can tag things however you want! But Ao3 also uses those tag wranglers you’ve heard about to track trends in tags and suggest a responsive controlled vocabulary. So if you tag Character A/Character B but others tag Character B/Character A, the wranglers combine those tags into a preferred term that Ao3 suggests when you start tagging your work. But Ao3 also lets you chat away in your tags, bringing the best of both worlds.
Anyway I spent 2 years getting a masters in library science and am 40k in debt, just to share this information with you. So go forth now armed with the knowledge that there are reasons some tagging systems are…better than others.