Arguably the first social media in existence at a time when only hobbyists owned a computer, Community Memory Terminals were set up in public places in 1973 with a telephone-modem connection. The “bulletin board” metaphor is often overused when it comes to electronic media, but it is very apt here, functioning as a digital version of a local bulletin board, where anyone could add notices, requests for help, help wanted, and so on, and through the modem, were visible from any terminal.
Reading was free. But leaving a post required a quarter or two.