Define Authentication.

 Authentication is the process of verifying the identity of an entity, such as a user, device, or system, to ensure that it is who or what it claims to be. It is a crucial aspect of information security and is used to grant or deny access to resources, data, or services based on the verified identity.

Authentication typically involves the presentation of credentials, such as usernames, passwords, tokens, or biometric data, to an authentication system. The system then compares these credentials with stored records or a trusted authentication server to validate the identity. If the presented credentials match the stored or trusted data, the authentication is successful, and the entity is granted the requested access privileges.

Authentication mechanisms can vary depending on the context and level of security required. Common methods include knowledge-based authentication (e.g., passwords), possession-based authentication (e.g., physical tokens), inherence-based authentication (e.g., fingerprints or facial recognition), and multi-factor authentication (a combination of two or more authentication factors).

The goal of authentication is to establish trust and prevent unauthorized access, impersonation, data breaches, and other security threats by ensuring that only authorized individuals or entities can access protected resources.