A policy is a collection of profile settings to which profiles or individual users can be assigned within an organization – such as a site or a school. The policies override the default profile or user settings.
You are allowed to combine different settings in a policy, as well as combine different policies for a profile or user.
With the use of policies, you have the ability to change the permissions for a set of users without having to edit the profile. This creates a more flexible system, allowing schools to have their own rules independently from the rest of a site’s schools.