http://blogs.technet.com/ad/archive/2009/05/26/thoughts-on-single-sign-on-and-credential-providers.aspxWe use the term single sign on (SSO) to describe a variety of behaviors in Windows and other applications where the result is simply to prevent the user from being prompted to provide their credentials again and again; to ideally enter their credentialsenCommunityServer 2.1 SP1 (Build: 61025.2)