William Ballard wrote:
I run Sid. Whenever Debian makes a major release, it doesn't affect me at all, right, because in theory I'm already running the same or later versions of everything that's being released.
"The code name for Debian's development distribution is "sid", aliased to "unstable". Most of the development work that is done in Debian, is uploaded to this distribution. This distribution will never get released; instead, packages from it will propagate into testing and then into a real release [1]."
I think as much is said somewhere more officially and more explicitly, but don't know just offhand.
[1] http://www.debian.org/releases/unstable/ --dircha