Edit: a little digging and "A tilde is a multi-user online system designed to be a "home" for users by providing services such as shell access via SSH, email, small site hosting (on www, gopher, gemini), chat, or other programs. It is a loose term, akin to a public access unix systems (a.k.a. pubnixes), but with some connotations of a small community" https://tilde.wiki/wiki/Tilde