Complete index for pages on The Linux Information Project web site


Linux is a high performance, yet completely free, Unix-like operating system that is suitable for use on a wide range of computers and other products. Most distributions (i.e., versions) consist of a kernel (i.e., the core of the operating system) together with hundreds of free utilities and application programs in a coordinated package.

A narrower, and somewhat less common, meaning of the term Linux is just the kernel itself. However, when referring to just the kernel, usually the expression the Linux kernel is used.

Linux was started as a hobby in 1991 by Linus Torvalds while a student at the University of Helsinki (in Finland) because he was unhappy with the MS-DOS operating system that came with his new personal computer. He greatly preferred the much more powerful and stable UNIX that he had been using on the university’s computers, but he was not able to afford the high licensing fees for any of the commercial versions then available. Today, Torvalds remains the spiritual leader of the Linux movement, and he still coordinates the development of the Linux kernel.

UNIX Clone

UNIX was originally developed by Ken Thompson in 1969 at Bell Labs, the highly innovative research arm of AT&T (the former U.S. telecommunications monopoly). Much subsequent work was carried out at the University of California at Berkeley (UCB).

Linux is a clone of UNIX; that is, it was developed to mimic the form and function of UNIX but its source code was written completely independently (i.e., none of it was copied from UNIX source code). Source code is the version of an operating system or other software as it is originally written (i.e., typed into a computer) by a human in a programming language (e.g., the C language in the case of the Linux kernel).

Linux incorporates all of the features that have made Unix-like systems the longest-lived and what many consider to be the best operating systems still in widespread use. That is, it is a multiuser (i.e., allows multiple simultaneous users),multitasking, highly flexible (with regard to configuration), inherently secure (including high resistance to viruses, spyware and other malware) and extraordinarily robust (i.e., resistance to crashing and needing rebooting) operating system. A multitasking operating system is one in which multiple programs or processes (also referred to as tasks) can execute (i.e., run) on a single computer seemingly simultaneously and without interfering with each other.

As is the case with most of the Unix-like operating systems, Linux is a highly mature (and very sophisticated) work of engineering that has been skillfully crafted by the collective efforts of thousands of the best minds in computer science. There is no planned (and little unplanned) obsolescence.

Yet Linux is much more than just a clone of another highly successful operating system. It also represents a philosophy, one which not only incorporates the simple but elegant Unix philosophy but which also has also taken it a big step further and made it a truly free operating system.

Moreover, Linux is a product of the Internet era. In contrast to proprietary (i.e., commercial) operating systems, which have been developed mostly by paid programmers employed at corporations, Linux has been developed virtually since its inception by an informal, world-wide network of unpaid (but highly skilled and motivated) volunteers who communicate via the Internet.