apt stands for Advanced Package Tool; to install, delete or remove apps, keep the system up to date with security patches and more.

Add local directory to apt sources.list

autoremove

Display details about a package

Display package dependencies

Display policy of a package

Hold a package

Install a package

List packages

List all installed packages

List all repositories and PPAs

List packages that can be upgraded

Perform a full system upgrade

Purge a package

Remove a package

Search packages