Happy Birthday Linux! You're 25! When Linux was born on Aug. 25, 1991, it was little more than a hobby for then 21-year old Linus Torvald. Today the Linux community is estimated to be upwards of 86 million users strong. It has become the backbone of large enterprises, and it is installed in government systems and embedded in devices worldwide. The Linux operating system started out as an alternative to other platform architectures in use on mainframes and enterprise back-ends. It has grown into a major mainstream computing platform.