3) The Debian Project:
What is Debian? A little background:
Debian is an operating system, performing the same job as Microsoft Windows and Mac OSX do: running your computer. It has several major differences. It's Free in terms of both liberty and cost, and you are free to contribute to it. Due to the number of different architectures it runs on, it's flexibility and power, it is referred to as “The Universal Operating System.”http://www.debian.org/intro/abouthttp://wiki.debian.org/DebianIntroductionhttp://en.wikipedia.org/wiki/Debianhttp://d-i.alioth.debian.org/manual/en
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Debian gives you the choice of several kernels, or core operating programs, the most popular being the Linux kernel. The kernel is the software that interacts with your physical hardware and passes information to your application software. Debian tweaks the vanilla kernel for you, but you can get make your own modifications with tools Debian provides or use a vanilla kernel, too.http://www.kernel.org/http://en.wikipedia.org/wiki/Linux_kernel
Many of the programs used to write applications were created using the GNU tools. These include compilers, editors, linkers, debuggers, as well as most of the system-level commands:http://www.gnu.org/
All the software in the Debian system is free software that complies with the Debian Free Software Guidelines.(DFSG)http://www.debian.org/social_contract#guidelines
The Debian project recognizes the valuable input of both the GNU system and Linux kernel in the full name of the Debian OS, “Debian GNU/Linux.”
Who owns Debian?
You could say “No one” or “You do.” Unlike most other distributions, there is no company or magnanimous dictator behind it. It's users create it and share it. This is why you are encouraged to give back by what ever means you can, be it programming, graphic design, documentation, translating, or sharing your knowledge in the forum. If you can only contribute money, that's fine too.http://www.debian.org/social_contracthttp://www.debian.org/intro/help
To find out more about Debian finances see here:http://www.debian.org/donationshttp://www.spi-inc.org/
Applications that are deemed secure, stable, and free enough to be part of the Debian system are stored on servers, in “repositories” that are mirrored (duplicated) many times around the world. Here is a list of official Debian mirrors:http://www.debian.org/mirror/list
Along with the mirrors, many additional systems are used by the developers and maintainers to support the development process. Altogether, hundreds of dedicated machines and donated space on hundreds more support the creation and distribution of Debian GNU/Linux.
There are unofficial mirrors also. These may hold, for example, software that has possible patent issues in the USA where Debian is based. These issues may not apply in your country. Some DVD and mp3 software are examples that are not in the official repository but readily available:http://debian-multimedia.org/
The three main Debian branches:
Debian's distribution is divided into three primary branches; stable, testing, and unstable. So far in project history, they have always been named after characters from the Disney "Toy Story" movies.
Stable is currently Lenny.
Testing is currently Squeeze.
Unstable is always Sid.
You can use "stable" in your sources.list and when the current version of testing becomes stable your system will upgrade. If you want to run newer versions of certain applications on a stable system you can, via the unofficial but respected "backports" repository. This combination, stable plus backports, is a good recommendation for new users.http://www.backports.org/
That said "squeeze," the testing branch, is more stable than many other distributions' full releases, but you will occasionally have breakages or bugs that take time to be fixed. With care and a little understanding, it can be a solid, up-to-date desktop system.
To update biotube's great post:
Biotube wrote: Unstable (permanently Sid): When a new version of a package(or a new package all together) gets uploaded, it usually goes here. Sid machines can be highly volatile, (giving birth to the saying "If it breaks, you get to keep both halves"), although it's calmed down in recent years thanks to experimental.
Testing (currently "Squeeze"): After a while, a package in Sid with no really bad bugs gets moved here(the exact time depends on the urgency of the update). For this reason, it's much more stable than Sid. Since packages are updately fairly quickly, it's recommended for desktop users(don't let the name fool you - testing can be more stable than some distros' (especially the-one-that-cannot-be-named) releases).
Stable, (currently "Lenny", soon to be "Squeeze"): Every once in a blue moon, the Debian release team puts testing in what's know as "The Big Freeze". During this time, nothing but bugfixes may be moved to testing. Once all release-critical(RC) bugs are gone, testing becomes stable and a new testing branch is opened. Since only bugfixes are allowed in stable, the packages tend to get dated rapidly.
A new and really nice overviewhttp://pthree.org/2009/11/17/debian-the
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