Authentication

Authentication establishes the identity of a principal by validating one or more factors: something you know (password, PIN), something you have (security key, smartphone), or something you are (biometrics). Modern systems often combine factors (MFA), pair them with device posture signals, and rely on standards such as SAML, OAuth 2.0 and OpenID Connect to delegate the check to a trusted identity provider. Strong authentication is a prerequisite for any meaningful authorization decision and a top priority for stopping phishing, credential stuffing and account takeover. Weak or reused passwords without phishing-resistant factors remain the leading cause of initial access in breaches.