Ubuntu package not available

On a lot of forums, you can see:

sudo apt-get <package>

But sometimes this package is not available. What to do?

It is certainly that you did not add all the repositories available. Ubuntu comes with a preconfigured system that allows only to download ubuntu selected packages.

If your package is not present, you will have to add the repository...

The file containing repositories is /etc/apt/sources.list

By default, most of the repositories are commented (# symbol). Uncomment Universe (lines terminated by universe...) repositories and you should be able to download the package (most of the time).