Debian

Debian is one of the oldest Linux distributions. Debian has one of the largest official repositories of any Linux distribution.

Software
Debian has access to online repositories containing more than 50,000 packages. Officially, Debian only contains free software, but non-free software can be downloaded from the repositories. Debian ships with LibreOffice, Firefox ESR, VLC, GIMP, Evince, and more.

The latest release of Debian, 10.0, uses systemd as the default init system.

Desktop Environments
Debain offers ISO images specifically built for GNOME (the default), KDE, Xfce, LXDE, LXQt, MATE and Cinnamon. Other window managers, such as IceWM, Awesome, Enlightenment, Openbox, Fluxbox, and others are also available as packages.

The default desktop environment of version 7 was temporarily changed to Xfce, as GNOME did not fit within the limits of a CD. The default for version 8 was also temporarily changed to Xfce in November of 2013, but was restored to GNOME in September 2014.

Branches
There are three branches of Debian:
 * Stable is the current release and targets stable and well-tested software needs. Stable is made by freezing Testing for a few months where bugs are fixed and packages with too many bugs are removed; then the resulting system is released as Stable. It is updated only if major security or usability fixes are incorporated.undefined This branch has an optional backports service that provides more recent versions of some software.
 * Testing is the preview branch that will eventually become the next major release. The packages included in this branch have had some testing in Unstable but they may not be fit for release yet. It contains newer packages than Stable but older than Unstable. This branch is updated continually until it is frozen.
 * Unstable, always codenamed "Sid", is the trunk. Packages are accepted without checking the distribution as a whole. This branch is usually run by software developers who participate in a project and need the latest libraries available, and by those who prefer bleeding-edge software. Debian does not provide Sid installation discs. This branch can be installed through a system upgrade from Testing.

Codenames
The codenames of Debian releases are names of characters from the Toy Story films. Debian 10 was named "Buster", after Andy's pet dachshund in the Toy Story series. Debian 9 was named "Stretch", after the toy rubber octopus in Toy Story 3. Debian 8 was named "Jessie", after the cowgirl in Toy Story 2 and Toy Story 3. The Testing branch is currently named "Bullseye", after Woody's horse in the Toy Story series. The trunk is permanently named "Sid", after the emotionally unstable boy next door who regularly destroyed toys. This naming tradition came about because Bruce Perens was involved in the early development of Debian while working at Pixar.

Derivatives
Debian is one of the most popular Linux distributions, and many distributions have been based on the Debian codebase, including Ubuntu and Knoppix. According to Distrowatch, there are around 131 active Debian-based distributions. Debian encourages derivatives to merge their work back into Debian, as Ubuntu does with the Debian Package Tracker.

History
To date, Debian has made fifteen major stable releases.

Debian Live
Debian Live is Debian in a LiveCD or USB keys that can use DebianInstaller to install standard Debian into hard disk, or boot via LiveCD.