The Quality Profiles service is central to SonarQube, since it is where you define your requirements by defining sets of rules (ex: Methods must not have a complexity greater than 10).
Ideally, all projects will be measured with the same profile for any given language, but that's not always practical. For instance, you may find that:
Which is why you can define as many quality profiles as you wish. To manage quality profiles, go to Quality Profiles (top bar), where you'll find profiles grouped by language. Here's an overview of this page:
As you can see above, language plugins always come with a predefined built-in profile (usually called "Sonar way") so that you can get started very quickly with SonarQube analyses. This is why as soon as you install a new language plugin, at least one quality profile will be available for you.
Each language must have a default profile (marked with a green check). Projects that are not explicitly associated with a specific profile will be analyzed using the language's default profile.
The Quality Profiles service can be accessed by any user (even anonymous users). All users can view every aspect of a profile. That means that anyone can see which rules are included in a profile, and which ones have been left out, see how a profile has changed over time, and compare the rules in any two profiles.
To make rule profile changes (create, edit or delete) users must be granted the Administer Quality Profiles and Gates permission.
A project administrator can choose which profiles his project is associated with. See Project Administration for more.