External repositories are additional software package repositories that are not maintained by Debian. Before extrepo, maintainers of such repositories would suggest that you download and execute an (unsigned) shell script as root, or that you download and install their (unsigned) package, which is not ideal for security.

The extrepo package tries to remedy this, by providing a curated list of external repositories that can be enabled by a simple command, allowing unsigned scripts to be replaced by a simple "extrepo enable example.com_repo".

Note, however, that while the repositories are curated, and that any repositories with malicious content will be removed and/or disabled when detected, no warranty is made by the Debian project as to the security or quality of the software in these third-party repositories.