Linux distribution

A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions (often called distros for short) are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications. These operating systems consist of the Linux kernel and, usually, a set of libraries and utilities from the GNU Project, with graphics support from the X Window System. Distributions optimized for size may not contain X and tend to use more compact alternatives to the GNU utilities, such as BusyBox, uClibc, or dietlibc. There are currently over six hundred Linux distributions. Over three hundred of those are in active development, constantly being revised and improved.

Because most of the kernel and supporting packages are free and open source software, Linux distributions have taken a wide variety of forms—from fully featured desktop, server, laptop, netbook, mobile phone, and tablet operating systems as well as minimal environments (typically for use in embedded systems or for booting from a floppy disk). Aside from certain custom software (such as installers and configuration tools), a distribution is most simply described as a particular assortment of applications installed on top of a set of libraries married with a version of the kernel, such that its "out-of-the-box" capabilities meet most of the needs of its particular end-user base.

One can distinguish between commercially-backed distributions, such as Fedora (Red Hat), openSUSE (Novell), Ubuntu (Canonical Ltd.), and Mandriva Linux (Mandriva), and entirely community-driven distributions, such as Debian and Gentoo.

Notable distributions
The most common distributions are, as of december 2013 Some other notable Linux distros are:
 * the Debian family:
 * Linux Mint, a branch of Kubuntu/Ubuntu branched in 2009.
 * Debian GNU/Linux, initiated in 1993, known for its extreme stability and exceedingly long release scedule.
 * Ubuntu, a short release branch of Debian GNU/Linux starting from 2004.
 * Kali Linux, based on Ubuntu.
 * Tails - the anonym live-distro, based on Debian.
 * Ubuntu Ultimate Edition - the build based on Ubuntu. Project started from 2008.
 * Linux Lite is a Linux distribution, based on Debian and Ubuntu and created by a team led by Jerry Bezencon.
 * the Red Hat family:
 * Mageia, a branch from Mandriva initiated in 2011, Mandriva in its turn a merger of Mandrake and Conectiva, both being derived from Red Hat
 * Fedora, the free version of Red Hat, name changed from proprietarized Red Hat in 2003
 * OpenSUSE, branched from Red Hat in 1994.
 * ROSA Linux is a Russian distribution, fork of Mandriva.
 * OpenMandriva Lx is a fork of ROSA Linux
 * Arch Linux, a distro that by default installs a GUI-less but fully functional system,
 * GParted Live, a card-sized CD/USB distro used to boot and partition PC hard disks,
 * Kali, a Debian-based distribution with a collection of security and forensics tools,
 * Slackware, an old still pretty popular independent distribution from 1993
 * SystemRescueCd, a Gentoo-based distro for system rescue (voilá!)
 * Linux From Scratch, LSF, not a distro but a large document: if you want to learn the full installation process of a Linux by hand, this is the document for you. It will take weeks to accomplish, but after that, you're a Linux expert.