Final answer:
Authentication is the process that verifies the identity of a user when they request access to a computer system to ensure they are not an imposter.
Step-by-step explanation:
The process that ensures the person requesting access to a computer is not an imposter is Authentication. Authentication is vital for security measures, as it verifies the identity of users trying to access information in a computer system.
This is typically done by requesting the user to provide some form of evidence, such as a password, a biometric data, or an SMS code. Authentication can help prevent unauthorized access and protect the system from potential breaches.