federation
termsecuritynetworking
Accepting an identity proven somewhere else, so a user authenticated by their own organisation can reach a service run by another.
It moves the trust decision from a password to a relationship: the service no longer stores credentials, it decides which issuers it believes. The consequences are worth naming. Account lifecycle belongs to the issuer, so removing someone at home removes their access everywhere - which is the whole benefit and also means a compromised issuer is a compromise of every service that trusts it.
Also known as: identity federation