Definition
User authentication is the process of verifying the identity of a user attempting to access a system or resource. It ensures that the individual is who they claim to be before granting them entry, typically through credentials like usernames and passwords, security tokens, or biometrics. In practice, authentication systems compare the provided credentials against a stored database of valid information to confirm identity. This process is crucial for protecting sensitive data, maintaining system integrity, and preventing unauthorized access to networks and applications. For instance, logging into your email account uses user authentication to confirm your identity. It is distinct from authorization, which determines what an authenticated user is allowed to do. Understanding user authentication is fundamental for IT professionals and appears on certifications like CompTIA Security+ and AWS Certified Solutions Architect Associate.