उबुंटू दस्तऐवजीकरण संघ
Add repositories to extend the software sources Ubuntu uses for installation and upgrades.

# Add software repositories

Software is available from third-party sources, as well as from the default Ubuntu software repositories. If you want to install software from a third-party software repository, you must add it to Ubuntu's list of available repositories.

Only add software repositories from sources that you trust!

Third-party software repositories are not checked for security or reliability by Ubuntu members, and may contain software which is harmful to your computer.

To add a repository:

Open Software & Updates via the Activities search bar.

Switch to the Other Software tab.

Click Add and enter the APT line for the repository. This should be available from the website of the repository, and should look similar to:

`deb http://archive.ubuntu.com/ubuntu/ resolute main`

Click Add Source. Enter your password in the Authenticate window.

Close the Software & Updates window. App Center will then check your software sources for new software.

Most repositories provide a signing key to be able to verify downloaded packages. So in addition to the steps above, you should follow possible instructions on how to download and install the signing key (GPG key).