Sources for most of the information on this page:


  • repository: a searchable collection of packages.

  • archive: synonym for repository; in this document we use "archive" only when refering to a searchable and downloadable collection of Debian packages that contains a "dists/" directory at the top level.


A suite is "a repository holding one particular "branch" of Debian's development process". A suite undergoes changes as packages move in and out. The suite gets names assigned to it and these names can change over time.

Here is an example:

suite-A   testing, buster
suite-B   stable,  stretch, version-9.9

suite-A   testing,   bullseye
suite-A'  stable,    buster,  version-10.0
suite-B   oldstable, stretch, version-9.9
Note: suite-A' is a copy of suite-A on new release day

suite-A   testing,   bullseye
suite-A'  stable,    buster,  version-10.1
suite-B   oldstable, stretch, version-9

Be aware that most suites undergo changes all the time, so, for example, suite-A under AFTER NEW MAJOR RELEASE will have different contents than suite-A under AFTER NEW POINT RELEASE.

Some suites will stop changing, most notably, those suites associated with old releases.

Some suites are sets of a packages that are complete operating systems, e.g., stable, sid, etc., while some suites are sets of packages not meant to be a complete operating system, e.g., stable-proposed-updates, testing-updates.


In the context of Debian package repositories, the terms "distribution" and "suite" are used interchangably. From Glossary:

Distribution (distro, dist): [...] Used more generally (e.g. in sources.list(5)) as a synonym for suite; hence source URLs which put alongside all the other dists.


A Debian release is a distribution that has been or is going to be released.

Release version

Each release has a major version number and a minor version number. For example, Debian "wheezy" has major version 7. Every version (starting with "wheezy") also has a minor version number. When "wheezy" was released its version minor version number was "0". Thus, at the time of its release, the current release of Debian was version "7.0".

New releases come out roughly every two years.

Release codename

Every Debian release has a codename associated with the major version:

      7  wheezy
      8  jessie
      9  stretch
     10  buster
     11  bullseye
      *  sid

We will usually refer to a specific Debian release by codename (thus "Debian stretch").

The "sid" codename points to the development versions of packages that are being prepared for the next release.

See also the graph at the bottom of the Debian Releases page.

Release "suite name"

Several releases also have names that indicate how close they are to the most recently released version.

  • stable: points to the current supported release.

  • oldstable: points to the PREVIOUS supported version.

  • oldoldstable: points to the PREVIOUS to the PREVIOUS supported release.

  • testing: points to the next current development state of the next stable Debian distribution.

  • unstable: an alias for "sid"

  • experimental: points at the "experimental" distribution.

At the time of this writing this translated to:

      7  wheezy      oldoldstable
      8  jessie      oldstable
      9  stretch     stable
     10  buster      testing
     11  bullseye
      *  sid         sid

When buster is officially released, the above will change to:

      7  wheezy
      8  jessie      oldoldstable
      9  stretch     oldstable
     10  buster      stable
     11  bullseye    testing
      *  sid         sid

Notable distributions in each release

Each release consists of several sets of Debian packages called "distributions":

  • current release (e.g., "stretch"): current point release

  • proposed updates (e.g., "stretch-proposed-updates"): packages being prepared for next point release

  • updates (e.g., "stretch-updates"): updates for users who want to install on their systems before the next point release is made, such as updates to virus scanners and timezone data; all packages from stable-updates will be included in point releases

  • backports (e.g., "stretch-backports"): packages for a later version of software than that in the current release.

  • security updates (e.g., "stretch/updates"): security updates that need a timely release. Note that usually these packages are served from a different archive (e.g.,

  • experimental: packages in pre-alpha.

  • sid: all the active development of new Debian software and packaging happens here.

The Archive

Most Debian repositories consist of at least one, but sometimes more than one, archive. The most common archive is "debian" but there is also "debian-local", "ubuntu", etc. To reach these archives a URL like the following is usually used:


Some examples:              (Debian's main archive) (Debian's security archive)          (Debian's old release archive)

Structure of a Debian archive

Each archive contains a variety of files and directories. The most important are


The dists directory

The dists directory contains a set of files and directories for each Debian distribution. For example, here are some of the distributions in the main Debian mirror:              (archive root)        (all the distributions)

Files in a distribution

Each distribution contains several files and directories. The most important of these are


The Release file

This file contains information about the packages for this suite. The first few lines are fields:

Suite       (e.g., stable, oldstable-updates)
Version     (e.g., 8.5) [not always present]
Codename    (e.g., jessie, wheezy-updates)
Valid-Until (a date; see below)

The rest of this file is a list of files in the directory along with their checksums.

Each Release (or InRelease) file has a Valid_Until except for the current point releases as these are considered production releases and hence do not expire.


When a Debian client wants to get a package from a Debian repository, it starts with the repository URL. It then appends the archive name. Next, it indicates a suite. This gets it inside of one of the dists/ directories.

The client should then download the Release and Release.gpg file. It then runs the equivalent to

gpg --verify Release.gpg Release

The pool directory

The packages themselves are in the pool directory.


How to browse the Debian package repository

  1. Look at the sources.list file

     cat /etc/apt/sources.list
  2. You will see something like this:

     # The main Debian archive and source tree.
     deb stretch main non-free contrib
     deb-src stretch main non-free contrib
  3. You can browse the repo by taking one of the above URL's, appending dists, and then appending the distribution (in this case stretch), and then appending one of the "components" (i.e., main, non-free, etc.).