See http://www.debian.org/ for information about Debian GNU/Linux.
Three Debian releases are available on the main site:

Debian 2.2r5, or potato.  Access this release through dists/stable.
Debian 2.2r5 was released Thursday, January 10th, 2002.  Release notes,
including installation and upgrade information, are in
dists/stable/main/upgrade-$arch (where $arch is, e.g. i386).

Testing, or woody.  Access this release through dists/testing.  The
current tested development snapshot is named woody.  Packages which
have been tested in unstable and passed automated tests propogate to
this release.

Unstable, or sid.  Access this release through dists/unstable.  The
current development snapshot is named sid.  Untested candidate
packages for future releases.

Older releases of Debian are at http://archive.debian.org/debian-archive

--- Other directories:
doc             Debian documentation.
indices         Various indices of the site.
project         Experimental packages and other miscellaneous files.
tools           Tools for creating boot disks and booting Linux.