Finger: the 1971 social network that never died

The first social network, called Finger, originated in 1971 at the Stanford Artificial Intelligence Laboratory (SAIL). It was created to help researchers quickly identify who was connected to the WAITS time-sharing system. The creator, Les Earnest, designed Finger to display real names, locations, and how long each terminal had been idle.

This allowed researchers to efficiently locate colleagues in person rather than relying on the computer. The protocol was later formalized in RFC 742 by Ken Harrenstien in 1977. Finger displayed two text files in the user's home folder: .plan and .project. The .plan file served as a brief status update or changelog, while the .project file detailed a user's current project.

Users could read these files using a simple command like "finger your-user@your-host." The most famous example of a .plan file was John Carmack's, who documented his progress on video game engines from 1996 to 2010. Finger has been used to create real-world applications, such as a microswitch-based soda machine status display at Carnegie Mellon University.

The protocol is incredibly simple, requiring a single TCP connection on port 79 and plain text responses. This simplicity has allowed Finger to remain functional for over half a century, and it continues to be available on many systems today, including macOS and Unix-based operating systems.