Linux

World's most popular open source (non-proprietary) computer operating system (OS), favored because of its proven efficiency, dependability, and reliability. Linux implements the core ('kernel') of the unix OS, and runs on practically every type of hardware platform from hand-held devices to mainframe computers. Reported to be the fastest growing OS on servers, and the one with the lowest total cost of ownership (TCO), it is in public domain and may be downloaded free of charge from several websites. Invented by Linus Torvalds (born 1969 in Finland) when he was a student at Helsinki University, it is continuously being improved by the worldwide cooperative effort of thousands of volunteer programmers.