The GNU Project, started in 1984, had the goal of creating a "complete Unix-compatible software system" made entirely of free software.
MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum in 1987.
In 1991, LinusTorvalds began to work on a non-commercial replacement for MINIX while he was attending the University of Helsinki. This eventually became the Linux kernel.
