Glossary
Single Sign-On (SSO)
Single sign-on lets a principal authenticate once and carry that authentication into every service configured to trust the same identity provider, rather than maintaining a separate login for each. This reduces the number of passwords a person has to manage, which in turn reduces password reuse — one of the more common paths to account compromise.
It also concentrates risk: a single sign-on session compromised at its source grants an attacker reach into every service that trusts it, not just one. That concentration is why the identity provider behind a single sign-on setup deserves security scrutiny disproportionate to its apparent size.