In 1991 Linus Torvalds, at the time studying in Helsinki, Finland, created the very first version of Linux for his own needs. This very rudimentary program was intended to run on the PC 80386 of the age. But Linus Torvalds had the good idea of making it "free" and to involve all those who wanted it. Thanks to the support of the emerging Internet network and the new born community of developers, but also thanks to the preexistance of the Gnu project ([footnate] http://www.gnu.org) started some years earlier by Richard Stallman, Linux went on to become some years later a full operating system. Its power is unrivalled, its stability is now legendary and it improves with every day!
Linux is distributed by means of multiple "distributions" of which the very first were called SLS or Slackware2.1. Certain distributions are purely commercial like Caldera Open Linux2.2. Other are totally "free" like Debian2.3. Between the two and of special note is Red Hat Linux2.4 which is a much sought after Linux distribution, particularly due to its relatively simple installation procedure.