Debian is a computer operating system composed of software packages released as free and open source software especially under the GNU General Public License and other open source licenses. The primary form, Debian GNU/Linux, which uses the Linux kernel and GNU OS tools, is a popular and influential Linux distribution. It is distributed with access to repositories containing thousands of software packages ready for installation and use. Debian is known for strict adherence to the Unix and free software philosophies as well as using collaborative software development and testing processes. Debian can be used as a desktop as well as server operating system.
The Debian Project is governed by the Debian Constitution and the Social Contract which set out the governance structure of the project as well as explicitly stating that the goal of the project is the development of a free operating system. Debian is developed by over one thousand volunteers from around the world and supported by donations through several non-profit organizations around the world. Most important of these is Software in the Public Interest, the owner of the Debian trademark and umbrella organization for various other community free software projects.
Little video review from YouTube
Thus, the Debian Project is an independent decentralized organization; it is not backed by a company like other Linux distributions such as Ubuntu, openSUSE, Fedora, and Mandriva. The cost of developing all the packages included in Debian 4.0 etch (283 million lines of code), using the COCOMO model, has been estimated to be close to US$13 billion. As of April 2, 2009, Ohloh estimates that the codebase of the Debian GNU/Linux project (45 million lines of code), using the COCOMO model, would cost about US$819 million to develop.
Many distributions are based on Debian, including Ubuntu, MEPIS, Dreamlinux, Damn Small Linux, Xandros, Knoppix, BackTrack, Linspire, sidux, Kanotix, Parsix and LinEx, among others.
Debian is known for an abundance of options. The current stable release includes over twenty five thousand software packages for twelve computer architectures. These architectures range from the Intel/AMD 32-bit/64-bit architectures commonly found in personal computers to the ARM architecture commonly found in embedded systems and the IBM eServer zSeries mainframes. Prominent features of Debian are the APT package management system, repositories with large numbers of packages, strict policies regarding packages, and the high quality of releases. These practices allow easy upgrades between releases as well as automated installation and removal of packages.
The Debian standard install makes use of the GNOME desktop environment. It includes popular programs such as OpenOffice.org, Iceweasel (a rebranding of Firefox), Evolution mail, CD/DVD writing programs, music and video players, image viewers and editors, and PDF viewers. There are pre-built CD images for KDE, Xfce and LXDE as well. The remaining discs, which span five DVDs or over thirty CDs, contain all packages currently available and are not necessary for a standard install. Another install method is via a net install CD which is much smaller than a normal install CD/DVD. It contains only the bare essentials needed to start the installer and downloads the packages selected during installation via APT. These CD/DVD images can be freely obtained by web download, BitTorrent, jigdo or buying them from online retailers.
Here is some history of Debian Linux
Debian was first announced on 16 August 1993 by Ian Murdock. Murdock initially called the system "the Debian Linux Release". Prior to Debian's release, the Softlanding Linux System (SLS) had been the first Linux distribution compiled from various software packages, and was a popular basis for other distributions in 1993-1994. The perceived poor maintenance and prevalence of bugs in SLS motivated Murdock to launch a new distribution.
In 1993 Murdock also released the Debian Manifesto, outlining his view for the new operating system. In it he called for the creation of a distribution to be maintained in an open manner, in the spirit of Linux and GNU. He formed the name "Debian" as a combination of the first name of his then girlfriend Debra Lynn and his own first name. Murdock and Lynn later married, then filed for divorce on the week of 2007-08-10.
The Debian Project grew slowly at first and released the first 0.9x versions in 1994 and 1995. The first ports to other, non-i386 architectures began in 1995, and the first 1.x version of Debian was released in 1996. In 1996, Bruce Perens replaced Ian Murdock as the project leader. In the same year, fellow developer Ean Schuessler suggested that Debian should establish a social contract with its users. He distilled the resulting discussion on Debian mailing lists into the Debian Social Contract and the Debian Free Software Guidelines, defining fundamental commitments for the development of the distribution. He also initiated the creation of the legal umbrella organization, Software in the Public Interest.
Perens left the project in 1998 before the release of the first glibc-based Debian, 2.0. The Project elected new leaders and made two more 2.x releases, each including more ports and packages. The Advanced Packaging Tool was deployed during this time and the first port to a non-Linux kernel, Debian GNU/Hurd, was started. The first Linux distributions based on Debian, namely Libranet, Corel Linux and Stormix's Storm Linux, were started in 1999.
In late 2000, the project made major changes to archive and release management, reorganizing software archive processes with new "package pools" and creating a testing distribution as an ongoing, relatively stable staging area for the next release. In the same year, developers began holding an annual conference called DebConf with talks and workshops for developers and technical users.
In July 2002, the Project released version 3.0, codenamed woody, a stable release which would see relatively few updates until the following release, 3.1 sarge in June 2005.
There were many major changes in the sarge release, mostly due to the large time it took to freeze and release the distribution. Not only did this release update over 73% of the software shipped in the previous version, but it also included much more software than previous releases, almost doubling in size with 9,000 new packages. A new installer replaced the aging boot-floppies installer with a modular design. This allowed advanced installations (with RAID, XFS and LVM support) including hardware detection, making installations easier for novice users. The installation system also boasted full internationalization support as the software was translated into almost forty languages. An installation manual and comprehensive release notes were released in ten and fifteen different languages respectively. This release included the efforts of the Debian-Edu/Skolelinux, Debian-Med and Debian-Accessibility sub-projects which boosted the number of educational packages and those with a medical affiliation as well as packages designed especially for people with disabilities.
Debian 4.0 (etch) was released April 8, 2007 for the same number of architectures as in sarge. It included the AMD64 port but dropped support for m68k. The m68k port was, however, still available in the unstable distribution. There were around 18,200 binary packages maintained by more than 1,030 Debian developers.
Debian 5.0 (lenny) was released February 14, 2009 after 22 months of development. It includes over 25,000 software packages. Support was added for Marvell's Orion platform and for netbooks such as the Asus Eee PC. The release was dedicated to Thiemo Seufer, an active developer and member of the community who died in a car accident on December 26, 2008.
I would say, if you need a stable OS to install on your servers, Debian would be a really good choice!