What Is Debian Linux?

What Debian Linux Is and Where It Came From

Debian Linux is a free, community-developed distribution of the Linux operating system, known for its stability and its strict commitment to free software. A distribution, often called a distro, combines the Linux kernel with tools, libraries, default settings and a package manager to form a complete system.

Debian was started in 1993 by Ian Murdock. Its development is carried out by a worldwide group of volunteers rather than a single company. Decisions are governed by a published constitution and a social contract that commits the project to free software.

Because no commercial vendor controls Debian, its direction is set by its members. Support comes from the community and from independent companies. For the broader picture of how distributions are grouped, see what a Linux distribution is.

How the Stable, Testing and Unstable Branches Differ

Debian keeps three branches of development running at the same time. Each one trades freshness against predictability.

• Stable is the release recommended for servers. Its packages are tested for a long time before release, and afterwards they receive mostly security and critical fixes, so software versions change very little.
• Testing holds packages being prepared for the next stable release. It is more current than stable but can be unreliable at times.
• Unstable, also called sid, is where new packages first arrive. It changes constantly and is aimed at developers and experienced users.

A server running Debian stable keeps the same behavior for years, which suits sites that must not change unexpectedly. The trade-off is that the software may be older than the newest upstream releases. Teams that need a newer feature can use backports, which are newer packages rebuilt for stable.

Why Debian Matters Beyond Its Own Installs

Debian is also the foundation for other systems. Ubuntu Server and the desktop edition of Ubuntu are built on Debian's packages and tools. Software packaged for Debian therefore often installs on its derivatives, which gives Debian an influence well beyond its own user base.

Debian uses the .deb package format and the APT package manager, the same tools Ubuntu uses. Skills learned on Debian transfer well to Ubuntu. For a closer look at the trade-offs between the two, read Ubuntu vs Debian for servers.