Sharepoint 2010 supports following authentication methods- 1. Claims Aunthentication:- Claims authentication is buils on windows identity foundation which is a set of .Net framework classes that are used to implement Claims based identity. 2. Windows Authentication:- Standard IIS windows authentication methods are supported.Below are the following types of windows authentication: a. Anonymous b. Basic c. Digest d. Certificates e. Kerberos f. NTLM3. Form Based authentication:- Forms-based authentication enables SharePoint Server 2010 to work with identity management systems that implement the MembershipProvider interface. Below are the following types of FBA authentication:?Lightweight Directory Access Protocol (LDAP)?SQL database or other database?Other forms-based authentication solutions