Debian includes a wide variety of software as possible. As of this writing, the Debian stable distribution contains over 48,000 pre-compiled in the latest stable version. According to some counts, this is more than any other Linux distribution. To be fair, many of these are niche applications that do not have a wide user base. But the number of packages is only a part of the story.
The support of many different environments is also a distinguishing characteristic of Debian distributions, and probably one of the most startling. In fact, Debian is unique in the number of different processors supported. At the time of writing, they include both 32-bit and 64-bit Intel and AMD chips, ARM (EABI or little endian version), Intel Itanium, MIPS (both big and little endian), PowerPC (yes, this means it will run on ffiM servers!), System/390 (the old ffiM architecture), and SPARe. In addition, the Alpha architecture was supported up until Debian 6.0, and there are unofficial ports to other ARM architectures as well as Amtel's RISC chip (A VR32), HP's PA-RISe chip (up until Debian 6.0), the Motorola 68000, ffiM system Z, and Hitachi SuperH processors. There is also support for FreeBSD as the primary operating system instead of Linux on Intel 32-bit and 64-bit architectures, and there are other unofficial or experimental non-Linux-based Debian distributions for the GNU Hurd operating system.
This commitment results in a distribution that is extremely flexible, which can be used in a great many environments. Because of this, the Debian developers have chosen not to design a default installation package suitable for most users. A default Debian installs (with no optional software selected) includes only the basics. The administrator is expected to select as options, or install later, the appropriate software. This is not difficult as the base system includes everything necessary to easily install additional software.
This contrasts with Ubuntu Linux, which is based on Debian. A basic Ubuntu installation is designed to work out of the box for the majority of users. Thus, it includes more software, making it an appropriate distribution for a new Linux user without extensive knowledge of what may be available, or a preference for exploring what is there, as opposed to wading through packages offered for optional installation. However, this may also result in an installation with unnecessary components. Of course, they may be easily removed, but it is another example of choosing the proper distribution to reduce the administrator's workload.
This is one reason Debian is one of the major players in commercial servers, as only the software and services necessary are installed, which generally leads to better performance and simpler system management. This also means that Debian will run acceptably on older, poorer performing equipment. Note that, in spite of this, it is also most certainly possible to install a wide variety of software, both during and after installation, which will allow a Debian system to fulfill even the most insatiable developers.
