On September 17, 1991, the Finnish student of computer science Linus Torwalds uploaded Linux kernel version 0.01 of his later to become famous operating system Linux to the ftp server ftp.funet.fi and made it publicly available.
L. Torvalds. Proceedings of the AUUG94 Conference: Open systems. Looking into
the future: 6--9 September 1994, World Congress Centre, Melbourne,
Australia, page 9--14. Kensington, NSW, Australia, AUUG Inc, (1994)