In the Application Security section, you have the ability to define permissions, rights, and policies for individual Web applications that can restrict the rights the users have throughout the Web application and all its associated sites. Like everything with the security configuration, you must ensure that you select the correct Web application in the management control; otherwise, you might stop valid users from performing their required roles. There are five configurable security options and each plays a different role in applying security at different levels in the Web application. The five options are as follows:
Security For Web Part Pages
Self-Service Site Management
User Permissions For Web Application
Policy For Web Application ...