World’s most popular non-proprietary open source computer operating system (OS). Its proven efficiency, dependability, and reliability is the reason for its popularity. Linux runs the UNIX OS core ‘kernel’ on nearly every hardware platform, from mainframe computers to handheld devices. The fastest growing server OS, it has the lowest total cost of ownership (TCO). Public domain, no-cost free-of-charge download from several websites is unbeatable. It is continuously being improved by the worldwide cooperative effort of thousands of volunteer programmers. Linux Torvalds (born 1969 in Finland) invented Linux as a student at Helsinki University,