Debian is the oldest and most important Linux distribution entirely based on the collaborative work of volunteers worldwide. Even if the single people working on Debian may work on specific companies, the whole project does not have direct ties to a commercial entity or company.
It's probably the most impressive example of distributed, open source, collaborative software development, probably even more than the same Linux kernel. The Debian Project was officially founded by Ian Murdock on August 16th, 1993 and is considered one of the "purest" Linux distro in terms of independence from business logics and adherence to the free software standards.
Chronology of Debian releases
Debian 0.01 through 0.90 (August-December 1993). Mainly packaged by Ian Murdock with the help of few volunteers.
Debian 0.91 (January 1994). Introduction of a simple package system.
Debian 0.93R5 (March 1995): Responsibility for each package was clearly assigned to a developer (maintainer). dpkg introduced.
Debian 0.93R6 (November 1995): dselect appears. Last version with a.out binaries.
Debian 1.0 was never released for a naming problem with a CD vendor,
Debian 1.1 Buzz (June 17th, 1996): This was the first Debian release with a code name. This release was fully ELF, used Linux kernel 2.0, and contained 474 packages.
Debian 1.2 Rex (December 12th, 1996): This release consisted of 848 packages maintained by 120 developers
Debian 1.3 Bo (June 5th, 1997): This release consisted of 974 packages maintained by 200 developers.
Debian 2.0 Hamm (July 24th, 1998): This was the first multi-architecture release of Debian, adding support for the Motorola 68000 series architectures. This release made the transition to libc6, and consisted of over 1500 packages maintained by over 400 developers.
Debian 2.1 Slink (March 9th, 1999): Two more architectures were added, Alpha and SPARC. This release consisted of about 2250 packages and required 2 CDs in the official set. The key technical innovation was the introduction of apt, a new package management interface.
Debian 2.2 Potato (15 August 2000): This release added support for the PowerPC and ARM architectures, it consisted of more than 3900 binary packages derived from over 2600 source packages maintained by more than 450 Debian developers.
Debian 3.0 Woody (19 July 2002): New architectures were added: IA-64, HP PA-RISC, MIPS (big endian), MIPS (little endian) and S/390. This is also the first release to include cryptographic software due to the restrictions for exportation being lightened in the US, and also the first one to include KDE. It boasts more than 900 Debian developers, around 8500 binary packages and 7 binary CDs in the official set.
Debian 3.1 Sarge (6 June 2005): Awaited for long, Sarge got stable after many months of freeze and testing. It boasts many updates, 9000 new packages (among these OpenOffice, Thunderbird and Firefox), kernel 2.4 and 2.6, better multilanguage support and a renewed installation tool. A Major milestone in Debian history.
An overview of Linux Distributions: companies, entities, individuals and their efforts.
OS Guide: DebianThe OpenSkills Guide for Experienced Linux Sysadmin: Debian