Last Friday, legendary MIT computer scientist Fernando “Corby” Corbató passed away at his home in Newton, Massachusetts. He was 93. The Oakland-born researcher was responsible for several pivotal advances in the computer science space, most notably the password, which he invented during his pioneering work in computer time sharing.

Corbató led the development of the Computer Time-Sharing System (CTSS), which is regarded as one of the world’s first operating systems. This allowed multiple people to use a computer at the same time, accelerating the pace in which programmers worked. It’s also credited as the first computer system to use passwords.