SharePoint 2013 Claim Based Authentication

SharePoint 2013 supports only Claim Based Authentication, though the preview version supports the Classic Windows authentication, it will be removed when the actual release roles out.

Authentication is the process by which the system validates the user and allows/denies access to the user.

In Classic windows authentication, the users are configured in the Windows server and their credentials are validated when the user logs into to Server.

In Claim based authentication an individual provider validates the credibility of the user and proved a security token, the security token can contain multiple claims each of which contains unique information about the user. Examples of claims are User Name, SSN etc.

The following claim based authentication methods are supported in SharePoint 2013

   Windows claims using Windows Identity Foundation
   Security Assertion Markup Language based claims
   Forms-based authentication based Claims

To know more about these refer to the following posts.
Claim Based Authentication
Windows Identity Foundation
Security Assertion Markup Language (SAML)

Related Post
SharePoint 2013 Hardware and Software Requirements
SharePoint 2013 Authentication
SharePoint 2013 Sites
SharePoint 2013 Communities
SharePoint 2013 Content
SharePoint 2013 Search
SharePoint 2013 Insight
SharePoint 2013 Composites
SharePoint 2013 Claim Based Authentication
SharePoint 2013 Support for OAuth 2.0
SharePoint 2013 Distributed Cache Service