What command is used to add a repository in a system using APT?

The command used to add a repository in a system utilizing the Advanced Package Tool (APT) is "add-apt-repository." This command is specifically designed to facilitate the management of software repositories in Debian-based systems like Ubuntu. When executed, it allows users to easily add new repositories to the system's APT sources list by specifying the repository's address, enabling the installation of software packages from that repository.

By using "add-apt-repository," users can quickly enrich their software sources and ensure that they have access to the latest versions of applications and libraries that may not be available in the default repositories. This command also handles the necessary updates to the sources list automatically, streamlining the process of managing software installations.

Understanding this command is crucial for users looking to customize their Linux environments by incorporating additional software not provided in the standard repositories.