A quality profile is the place where you define your requirements for the code by configuring a set of rules against which it will be measured. This means finding which rules you want to activate on your profile, and setting the properties (severity and potential rule-specific parameters) you want for those rules in your profile.
Finding rules and managing their profile associations is the purpose of the Rules page.
Note that to be able to configure rules on a quality profile, you must have the Administer Quality Profiles and Gates permission.
Whatever search you're doing on the Rules page, you always have the opportunity to activate the rule you're looking at on a quality profile (assuming you're logged in and have the correct permissions).
For instance, let's say that you're browsing all the rules tagged as "bug" and you find that one is not activated in any of your profiles:
Once the rule is activated, it appears in the list of the "Quality Profiles" section:
Note that you do not necessarily need to do this activation rule by rule. You have the option to bulk activate/deactivate all the rules returned by your search for a single profile:
During a bulk activation:
In the Rules page, the "Quality Profile" criterion (always on top) allows you to concentrate on managing a specific quality profile instead of looking at any available rule. This criterion can be activated:
As you can see, when the "Quality Profile" criterion is activated/set, other criteria are also automatically displayed:
The "Quality Profile" rule header is used to focus your attention when browsing rules: when your search is profile-specific, a top bar is added on each rule to show its status (activated or not) within the profile, and to provide all the shortcut actions to activate/deactivate/update it on the specified quality profile:
Also, you will notice that the bulk action menu (accessed by clicking on the gears icon at the top right of the list of rules) offers new shortcut entries when your search is qualified by profile to bulk activate/deactivate the rules on the selected quality profile ("Activate in XXX" or "Deactivate in XXX").