The Linux kernel was originally created by Linus Torvalds, a Finnish computer science student, and first announced to the world on August 25, 1991—exactly 20 years ago today. At the time, Torvalds described his work as a "hobby" and contended that it would not be "big and professional" like the GNU project.
But the Linux kernel turned out to be one of the most significant pieces of open source software ever developed. Over the past two decades, it has grown from a humble hobby project into a global phenomenon that runs on everything from low-cost e-book readers to a majority of the world's supercomputers. Here's how it grew.