Contrary to what Silicon Valley would like you to believe, the rise of social computing--using computers to connect people and enable them to interact, collaborate, and communicate--not only happened long before the personal computer era even got underway, but it happened far from California. The PLATO computer system, launched in 1960 at the University of Illinois at Urbana-Champaign, was designed to be a platform for online learning, but by the early 1970s it had evolved into something much more, thanks to a growing, enthusiastic user community, many of whom were high school and college students. Within one 12-month stretch between 1973–74, PLATO's users created online message forums, chat rooms, graphical multiplayer games, instant messaging, email, and even early forms of emoji. Why have these early innovations--which disrupt the generally accepted computer history timeline--been largely forgotten? The fact is, they were not forgotten.