Which process prevents unrecognized users from gaining access to a system?

Authentication is the process that ensures only legitimate users are able to access a system by verifying their identity. This typically involves the use of credentials such as usernames and passwords, biometric data, or security tokens. When a user attempts to log in, the system checks their provided credentials against a stored database to confirm whether they are valid. If the authentication process fails, the user is denied access, effectively preventing unrecognized individuals from gaining entry into the system.

In contrast, while other processes like authorization and intrusion detection contribute to overall security, they serve different purposes. Authorization determines what actions an authenticated user is permitted to perform, and intrusion detection focuses on identifying unauthorized activity after access has been granted. Traffic monitoring, on the other hand, involves keeping an eye on network traffic to detect anomalies but does not directly manage user access.