Authentication is the process of verifying the identity of a person or device. It is a security measure that is used to confirm that a user or device is who or what it claims to be. Authentication typically involves verifying the person's or device's credentials, such as a username and password, a security token, or a biometric scan. 

There are different types of authentication methods, including: 

• Something you know: This could be a password, PIN, or a secret answer to a security question. 
• Something you have: This could be a security token, such as a mobile phone or hardware token that generates a one-time password. 
• Something you are: This could be a biometric characteristic, such as a fingerprint, facial recognition, or iris scan. 

The level of authentication needed depends on the sensitivity of the information being accessed and the potential impact of unauthorized access.