Membership and Role Management has always been a part of ASP.NET core infrastructure since 2.0. However, the default membership and role provides a rigid terms of database schema and the way information are stores. SimpleMembership simplifies all that. This is because it extends the core membership and role providers so so you use a custom database to store user information.
SimpleMembership is introduced with WebMatrix and tries to address the common membership and role issue by offering a more flexible model for authenticating users.
Read more about what SimpleMembership can do for you here:Â http://www.codeguru.com/csharp/.net/net_asp/mvc/using-simplemembership-in-asp.net-mvc-4.htm