Authentication modes — classic or claims-based
When create a new web application, you can select which authentication mode will be used in this web app.
Authentication modes determine how client computers authenticate with SharePoint Server 2010 resources.
Applications that support claims-based authentication obtain the security token from the user and use the information within the claims to determine access to resources. For new deployments of SharePoint Server 2010, Claims-based authentication is recommended. If you use claims-based authentication, all supported authentication methods are available for your Web applications.
What claims based authentication gives you, is for claims aware applications it will do some like this:
- When you enter you credentials these are sent to a Secure Token Service (from a page associated with the this service) which authenticates who you are. Other applications (that are claims aware trust the token service – believe that it tells them that you are who you are.
- You are then redirected back your SharePoint site, along with a token which SP and other claims apps can check against to see what you a authorized to access.
Classic mode authentication supports only Windows authentication.