tl;dr: Finger, a 1971 protocol from Stanford's AI Lab, was arguably the first social network: users published a plain-text `.plan` file readable by anyone via `finger user@host` on TCP port 79, famously used by John Carmack as a dev journal and even by a CMU Coke machine (an early IoT device). It fell out of favor after the 1988 Morris worm exploited a `fingerd` buffer overflow, but the protocol still ships on macOS, Linux, and Windows, and is seeing a small-web revival via services like Happy Net Box, Finger.Farm, and plan.cat.