Linux is 25 years old in 2016, but no one really knows when it really started. From CW.
We could consider Linux’s 25th birthday to be August 25th. That’s because on that date in 1991, Linus Torvalds made his announcement to the minix community to let them know that he was working on a modest new OS. He had started the work in April. By October 5th, he felt that his new OS was usable and ready for the community at large.
Whether you count the announcement (8/25/1991), its readiness for use/testing (10/05/1991), or Linus’ initially getting his project off the ground (April 1991) as the official birthday, Linux turns 25 sometime this year. And what is most amazing is what has happened since. All manner of Linux OSes have come into being.
Is it August 25th, 1991 or was it sometime in April 1991?