What Is Linux?
In 1991 Linus Torvalds developed the Linux operating system. Linux is a UNIX look alike operating system, but was a complete rewrite and was not developed from the main System V or BSD source code.
The objective for the Linux operating system was to develop an Open Source operating system. Open source means that the source code is freely available in the public domain. As a result of this there are now a number of variants of Linux including (to name but a few): RedHat, CentOS, Suse, Debian, Ubuntu, Fedora.