Explanation
When you create an Access Control Page using the Create Page Wizard, three of the following Access Roles get created: Reader, Administrator, and Contributor. These roles are predefined by APEX and correspond to the authorization schemes that control the access to the application, pages, or page components1. Reader role grants read-only access to the application. Administrator role grants full access to the application, including administrative and edit privileges. Contributor role grants edit privileges to the application, but not administrative privileges2. Developer role is not a default Access Role created by the wizard, but you can create your own custom roles and assign them to users on the Application Access Control page.