LINUX

Linux is a Unix-like computer operating system. Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone.

The name "Linux" comes from the Linux Kernel started in 1991 by Linus Torvalds. The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. The GNU contribution is the basis for the alternative name GNU/Linux.
Predominantly known for its use in servers, Linux is supported by corporations such as Dell, Hewlett-Packard, IBM, Novell, Oracle Corporation, Red Hat, and Sun Microsystems. It is used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers, video game systems, such as the PlayStation 2 and PlayStation 3, several arcade games, and embedded device such as mobile phones, routers, and stage lighting systems.
Linux is a remarkably complete operating system, including a graphical user interface and other components usually found in comprehensive UNIX system. Although copyright are held by various creators of Linux’s components, it is distributed using the Free Software Foundation’s copy left stipulations that mean any modified version that is redistributed must in turn be freely available.

Linux is sometimes suggested as a possible publicly-developed alternative to the desktop predominance of Microsoft Windows. Although Linux is popular among users already familiar with UNIX, it remains far behind Windows in numbers of users. However, it use in business enterprises is growing daily,

Uses
As well as those designed for general purpose use on desktops and servers, distributions may be specialized for different purposes including: computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.

Linux is a widely ported operating system. While the Linux kernel was originally designed only for Intel 80386 microprocessors, it now runs on a more diverse range of computer architectures than any other operating system: in the hand-held ARM –based iPAQ and the mainframe IBM system z9, in devices ranging from mobile phones to supercomputers. Specialized distributions exist for less mainstream architectures. The ELKS ernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the μclinux kernel fork may run on systems without a memory management unit. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers, PADs, video games consoles, portable music players, and mobile phones.