In 1991 Linus Torvalds creates Linux, an offshoot of Unix. An outgrowth of the open source software movement, he developed the operating system specifically for use on personal computers. Based on the GNU kernel developed by programmer Richard Stallman, who advocated making source code freely available, it slowly caught on with Internet Service Providers and other small businesses who were attracted by the low cost and ability to tailor the open code to their needs. Legions of others wrote improvements, fixed bugs and shared information about it over the net. Today Linux is still going strong, especially in high end computing.