Final answer:
The process where a user is validated via a username and password is known as authentication. This security mechanism confirms a user's identity before granting access to a system. Authentication differs from authorization, accounting, and auditing, which have other roles in system security and management.
Step-by-step explanation:
The process in which a user is identified via a username and password is called authentication. This is a security mechanism used to ensure that the user attempting to access a system is indeed who they claim to be. During authentication, the system validates the provided credentials against its database. If the credentials match, access is granted. On the other hand, authorization refers to the process of determining whether a user has permission to access certain resources or perform specific actions within a system. Accounting typically refers to the tracking of resource consumption by users, and auditing involves the independent evaluation of records or activities to ensure compliance with established policies or procedures. Authentication is crucial in both personal and organizational contexts to protect sensitive data and maintain system integrity.