In Visual Studio 2013 we revamped the membership and authentication system for ASP.NET web developers.
We added ASP.NET Identity which is a modern membership system for ASP.NET applications. It includes features such as Two-Factor Authentication which is becoming a common practise for securing web applications. For more information on why did we create ASP.NET Identity please read http://www.asp.net/identity/overview/getting-started/introduction-to-aspnet-identity
As part of Microsoft OWIN Components (Katana) We also added support for OWIN and added OWIN middlewares such as OWIN Cookies (and more) which replaces the FormsAuthentication module. The move to be OWIN compliant Framework will allow us to build apps which are more flexible, portable, lightweight, and provide better performance. For more information please read http://www.asp.net/aspnet/overview/owin-and-katana/an-overview-of-project-katana
We are in the processing of adding documentation for these changes but we