Software Repositories

What are Repositories?

There are thousands of programs available to install on Ubuntu. These programs are stored in software archives (repositories) and are made freely available for installation over the Internet. This makes it very easy to install new programs in Linux, and it is also very secure, because each program you install is built specially for Ubuntu and checked before it is installed. To organise the software, Ubuntu repositories are categorised into four groups: Main, Restricted, Universe, and Multiverse.

The rationale used to determine which software goes into which category is based on two factors:

  • The level of support software development teams provide for a program.

  • The level of compliance the program has to the Free Software Philosophy.

You can find more information about the Repositories available on the website.

The standard Ubuntu Install CD contains some software from the Main and Restricted categories. Once your system is made aware of the Internet-based locations for these repositories, many more software programs are made available for installation. Using the software package management tools already installed on your system, you can search for, install and update any piece of software directly over the Internet, without the need for the CD.

Adding Extra Repositories

To install software from the “Universe” or “Multiverse” repositories:

  1. Open System->Administration->Software Properties .

  2. Select Add

  3. To use the “Universe” repository, turn on Community Maintained (Universe).


    Adding this repository will mean that the majority of the Free Software universe will be available to install on your system. This software is supported by a carefully selected group of volunteers within the Ubuntu Community, but is not supported by the core Ubuntu development team and may not include security updates.

  4. To use the “Multiverse” repository, turn on Non-free (Multiverse).


    Adding this repository will mean that software which has been classified as non-free will be available to install on your system. This software may not be permitted in some jurisdictions. When installing each package from this repository, you should verify that the laws of your country permit you to use it. Again, this software may not include security updates.

  5. Click Close to save your changes and exit.