Single Sign On (SSO) is an authentication scheme that allows a user to log in with a single ID and password to any of several related, yet independent, software systems.
True single sign on allows the user to login once and access services without re-entering authentication factors.
Benefits to SSO include:
Reduce password fatigue from different username & password combinations.
Reduce time spent re-entering password for the same identity.
SSO services use protocols such as SAML (Security Assertion Markup Language).
SAML is an extensible markup language (XML) standard that facilitates the exchange of user authentication and authorisation data across secure domains. SAML-based SSO services involve communications among the user, an identity provider that maintains a user directory and a service provider.