Linux

Linux (pronounced LIH-nuks) is an operating system for computers, comparable to Windows or Mac OS X. It was originally created starting in 1991 by Finnish programmer Linus (pronounced LEE-nus) Torvalds with the assistance of developers from around the globe. Linux resembles Unix, an earlier operating system, but unlike Unix, Linux is both Free Software and open source software -- that is, you can not only download and run it on your computer, but also download all the source code the programmers created to build the operating system. You can then modify or extend the code to meet your needs.

Linux runs on a wide variety of hardware platforms, from huge mainframes to desktop PCs to cell phones. It is licensed under the Free Software Foundation's GNU Project's GNU General Public License, version 2, which lets users modify and redistribute the software.

You can think of Linux as having two parts -- a kernel, which is the basic interface between the hardware and other system software, and the functions that run on top of it, such as a graphical user interface (GUI) and application programs.