The Debian GNU/Linux FAQ
Chapter 2 - Getting and installing Debian GNU/Linux

The official document giving installation instructions is the Debian GNU/Linux Installation Guide. We'll give some additional notes about getting and installing Debian GNU/Linux here.

2.1 What is the latest version of Debian?

Currently there are three versions of Debian GNU/Linux:

release 3.1, a.k.a. the `stable' distribution

This is stable and well tested software, it changes if major security or usability fixes are incorporated.

the `testing' distribution

This is where packages that will be released as the next `stable' are placed; they've had some testing in unstable but they may not be completely fit for release yet. This distribution is updated more often than `stable', but not more often than `unstable'.

the `unstable' distribution

This is the version currently under development; it is updated continuously. You can retrieve packages from the `unstable' archive on any Debian FTP site and use them to upgrade your system at any time, but you may not expect the system to be as usable or as stable as before - that's why it's called `unstable'!

Please see How many Debian distributions are there in the dists directory?, Section 5.2 for more information.