Permissions are used to restrict or give access to users in your site to perform various actions or view certain information.
This video provides a brief overview of the permissions available.
Broad permissions may be configured to determine just how much information you would like to allow your users to access. The three access types for broad permissions are None, View, and Full.
Detailed permissions may be configured to determine the actions for which your users are allowed to take. These permissions are customizable on any given page.