Why Claim based authentication instead of role based authentication

Question

I am new to claim based authentication. I have gone throught several aricles and could not able to figure out the exact use of claim based authentication. Here are some doubts I have about claim based authentication.

1. I would like to know what is the difference and advantages of claim based over role based authentication.
2. Can we connect to Sql Server 2008 R2 using claim based authentication instead of ADFS? If, so how?
3. Advantage of using claim based authentication in WCF?

Can anyone provide me with some explanations, so that I can understand Claim based authentication and use with my application?

Answer 1

In addition - claims have nothing to do with authentication.

There is no such thing as claims- or role-based authentication. It is about modeling identity in a way your application can work with.

Roles are also claims (with a fixed true/false value) - claims just give you more expressiveness with key/value pairs.