Linus Benedict Torvalds was a 21-year-old student at the University of Helsinki when he posted his now-famous note to the comp.os.minix newsgroup on August 25, 1991. Writing from the address torvalds@klaava.Helsinki.FI, he announced that he was “doing a (free) operating system (just a hobby, won’t be big and professional like gnu) for 386(486) AT clones.” That hobby kernel became Linux.
His early posts show a developer working closely against Andrew Tanenbaum’s MINIX, the teaching operating system Torvalds had been using. The August 1991 message notes that his system was “free of any minix code” and that it had “a multi-threaded fs,” features he contrasted with MINIX as he built out his own kernel.
In 1992 Torvalds defended his design publicly in the comp.os.minix thread later reproduced as an appendix in the O’Reilly book “Open Sources.” There he answered Tanenbaum’s “LINUX is obsolete” critique directly, conceding that “from a theoretical (and aesthetical) standpoint linux looses” to a microkernel while arguing that his monolithic kernel was the more practical choice for the hardware he had.
Beyond the kernel, Torvalds went on to create git, the distributed version control system that now underlies much of modern software development, and he has continued to coordinate Linux kernel releases over the decades that followed.