Authentication is the process of verifying the identity of a user, device, or system before granting access to resources or information. It ensures that individuals are who they claim to be, helping to protect sensitive data and maintain security.

Key Types of Authentication:

1. Knowledge-based: Involves something the user knows, such as a password or PIN.
2. Possession-based: Relies on something the user has, like a security token or smartphone.
3. Biometric: Uses unique physical characteristics, such as fingerprints or facial recognition.
4. Multi-factor Authentication (MFA): Combines two or more of the above methods to enhance security.

Effective authentication is crucial for preventing unauthorized access and ensuring the integrity and confidentiality of systems and data.