An authentication method is a specific mechanism or process used in cybersecurity to verify the claimed identity of a user, device, or system attempting to access resources or services. This verification forms a foundational component of Identity & Access Management (IAM), establishing authenticity before any authorization decisions can be made. Authentication methods rely on various factors to confirm legitimacy: something the user knows (like a password), something the user possesses (such as a security token), or something the user inherently is (biometric data like fingerprints).

These methods act as critical security gatekeepers, enforcing access policies and protecting sensitive information from unauthorized access. The effectiveness of an organization's security posture depends significantly on choosing robust and appropriate authentication methods, which help mitigate risks associated with impersonation and unauthorized system entry. Common examples include passwords, multi-factor authentication (MFA), biometric verification, smart cards, and certificate-based authentication, each offering different levels of security suited to various use cases and risk profiles.