Linux is an operating system created by Linus Torvalds while he was enrolled at the University of Helsinki in Finland. He began his work in 1991 when version 0.2 was released. In 1994, Linus released the the 1.0 version of the Linux Kernel.
Linux is released under the GNU General Public License which guarantees the freedom of its source code. This doesn't mean that Linux is free: companies and developers may charge money for it as long as the source code remains available. Used in many different environments, Linux is often considered an excellent, low-cost alternative to other more expensive operating systems.
The Linux Penguin, Tux, which you can see pictured on the right, is the official mascot of the Linux operating system. The word "Linux" is pronounced with a short "i" and with the first syllable stressed, as in LIH-nucks.
Read more about Linux on the Wikipedia web site.