Explanation:
Authentication is the process of verifying the identity of a user, device, or entity before granting access to a system or resource.

It ensures that only legitimate users can access sensitive data or services. Authentication methods include passwords, biometrics, and multi-factor authentication (MFA).

The strength of the authentication process directly impacts the security of digital systems and services.

Additional Information:
Single sign-on (SSO) and passwordless authentication are gaining popularity for improved user experience and security.

Authentication mechanisms are often complemented by authorization processes to define user privileges and access rights.

Formal Definition:
Authentication is the process of verifying the identity of an entity to ensure it is legitimate before granting access to resources or systems.