Debian Releases
In Debian terms, a distribution is a collection of specific package versions. From time to time, a distribution is declared ready for release and becomes a release. In practice, these two terms are often used interchangeably when referring to Debian distributions that have reached the "stable" milestone. Debian distributions are given code names (recent ones include potato, woody, and sarge, named for characters in the movie Toy Story) to identify their archive directory on the Debian servers. While a particular distribution release is active, it will be referenced by one of three release tags, each one pointing to one of the three active releases. The tags - unstable, testing, and stable - identify the state of the release within the release cycle. At the time of this writing, the current stable release is Etch, and the testing release is Lenny. The unstable release is special in that it is always named Sid (after the kid who broke all the toys).
New packages, and new versions of packages, are uploaded to the Debian archive and are imported into the unstable distribution. This distribution always contains the newest version of every package, which means that changes have not yet been thoroughly tested to verify that installing them will not cause unexpected behavior. Once a package has been assigned to the unstable area for a few days, and testing shows that it has not had any significant bugs filed against it, it is imported into the testing distribution. The testing distribution remains open to changes (just as the unstable area was) until it is frozen in preparation for release as the next stable distribution. When testing is in the frozen state, only changes necessary to fix significant bugs are imported.
After all release-critical bugs have been fixed in the frozen testing distribution, the release manager declares the release ready, and it replaces the stable distribution. The previous stable version becomes obsolete (but remains on the Debian archive for a reasonable period of time), a new testing distribution is created from the changes that went into packages in the unstable area while testing was frozen, and the process begins again.
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