Access Control Service (ACS) is one of the cloud-based services provided by Windows Azure. ACS allows you to easily authenticate and authorize the users to access your web applications and services while allowing the features of authentication and authorization to be factored out of your code. Instead of implementing the role-based authentication and authorization system with the user accounts that are specific to your application, you can let ACS orchestrate the authentication and much of the authorization of your users. With ACS, you can use the standards-based identity providers, which include the enterprise directories such as Active Directory and the web identities such as Windows Live ID, Google, Yahoo!, Facebook, and OpenID.