MustBe is not a complete authorization framework, with roles and responsibilities and models and data access and everything that you need. Rather, it is the underlying plumbing that you need to secure your site. It allows you to fill in the necessary parts to manage data access, roles and users, and gives you the activity based plumbing to secure it all. MustBe is an authorization system - the part of a security system that decides whether or not you are allowed to do something. This is the second of authentication and authorization, where authentication simply determines who you are.