Note: You will have to enter your password to change settings in this window.If you click "Select Best Server", Ubuntu will attempt (on this occasion only) to find the fastest server.Packages in PPAs do not undergo the same process of validation as packages in the main repositories.
If you have an internet connection you can install software from any Ubuntu repository.
The search box is an easy method to quickly locate a package maintained by the Ubuntu team.
Several input selections are available to help the user refine the search.
There are times when you might want to add extra repositories to your system's software sources (that is, in addition to the repositories provided by Canonical).
For example, there is at least one repository that "caters to the Ubuntu gamer".