The different versions of Debian has codenames taken from the computer animated movie ToyStory. At the present the following versions are widely used:
DebianPotato - the previous official released version of Debian. Released as stable August 15th 2000.
What to use
To choose which release might suit your requirements best read http://people.debian.org/~osamu/newbie.html#best [http://lists.debian.org/debian-devel/2003/debian-devel-200301/msg01753.html addendum]
There are also point releases, which are updates to the stable releases. For the most part, these just add security updates. Debian 2.2r7 was released on July 13th 2002.
Older releases include
- Unnamed - v0.91 - January 1994
- Unnamed - v0.93R5 - March 1995
- Unnamed - v0.93R6 - November 1995
DebianBuzz - v1.1 - June 1996
DebianRex - v1.2 - December 1996
DebianBo - v1.3 - July 1997
DebianHamm - v2.0 - July 1998
DebianSlink - v2.1 - March 1999
(Did I forgot a version - add it. If you know some highlights of the versions please add.)