-> Single Sign-On is a property of access-control of multiple related, but independent software systems. With this property a user logs in once and gains access to all systems without being prompted to log in again at each time. This is typically accomplished by using the Lightweight Directory Access Protocol (LDAP) and stored LDAP databases on servers.
-> Conversely, single sign-off is the property whereby a single action of signing out terminates access to multiple software systems.
-> Windows Integrated Single Sign-On
-> Extranet Single Sign-On (Web SSO)
-> Server-Based Intranet Single Sign-On
-> Enterprise Single Sign-On System