Much of why Debian is a strong Linux distribution comes from its package management. Everything in Debian – every application, every component – everything – is built into a package.
There are many software packages available for Debian – everything from the Linux kernel to games. And their number has been growing with every release.
The Apt (Advanced Package Tool) package management system is a set of tools to download, install, remove, upgrade, configure and manage Debian packages, and therefore all software installed on a Debian system.
Installing, removing, upgrading software
To manage installed software, use a package manager:
PackageManagementTools - List of package managers and related tools
DebianUpgrade - How to upgrade from a Debian release to another
SourcesList - Edit packages sources (repositories)
PackageInstallTips - Package management tips
AptConfiguration - Apt configuration and pinning
UnattendedUpgrades - Automatically install latest security (and other) upgrades
PackageManagement/Preseed - Preconfigure Debian packages before installation
PackageManagement/Searching - Searching for packages
DebianPackageManagement - Advanced topics on Debian package management
SecureApt - Authenticate packages against cryptographic signatures
Debian package documentation
Every Debian package installs its documentation under /usr/share/doc/<package_name>. Check this directory for more information on a specific package.
All programs provided by Debian packages come with their own ManPage.
DebianRepository/Setup - summarizes the process of setting up a Debian package repository
DebianRepository - Debian package repository
DebianRepository/Format - Debian package repository format
DebianRepository/UseThirdParty - Instructions to connect to a third-party repository
Packaging - Information relevant to developers wishing to package software for Debian.
https://www.debian.org/Bugs/ - information on finding, reporting and fixing bugs in Debian packages
AptProtocol - Installing packages by clicking on links with apt:// URLs
All wiki pages related to package management: