My bf has actually done each of these at least once 😆
Omfg I love him so much 😭🩷
yeah they're just a little note you can add to a user to help remember who's who, once you've got a few of them it can be quite fun to see familiar faces showing up in the most random places all over lemmy :3
they're purely a client-side feature and the official lemmy ui doesn't support them - personally i use Summit for Lemmy when browsing on mobile but i'm pretty sure most of the other popular mobile apps support tags as well