5.8 What are all those directories inside dists/stable/main?

Within each of the major directory trees[ 2], there are three sets of subdirectories containing index files.

There's one set of binary-something subdirectories which contain index files for binary packages of each available computer architecture, for example binary-i386 for packages which execute on Intel x86 PC machines or binary-sparc for packages which execute on Sun SPARCStations.

The complete list of available architectures for each release is available at the release's web page. For the current release, please see On what hardware architectures/systems does Debian GNU/Linux run?, Section 3.1.

The index files in binary-* are called Packages(.gz) and they include a summary of each binary package that is included in that distribution. The actual binary packages (for woody and subsequent releases) reside in the top level pool directory.

Furthermore, there's a subdirectory called source/ which contains index files for source packages included in the distribution. The index file is called Sources(.gz).

Last but not least, there's a set of subdirectories meant for the installation system index files. In the woody release, these are named disks-architecture; in sarge, they are at debian-installer/binary-architecture.