Conversation

So I realize I've been thinking of social networks as graph-based and set-based.

Graph-based means you follow other users and get a feed of their posts. (E.g. Facebook, Goople, birdsite, here).

Set-based means you are either in or out and if you're in, your feed is the same as everyone else who's in. (E.g. subreddits, mailing lists, USENET groups, web fora.)

I'm finding this to be a useful distinction.