Definition
Authentication is the process of verifying the identity of a user, device, or system attempting to access a resource. It answers the question, "Are you who you claim to be?" This is typically achieved by requiring credentials, such as a password, biometric scan, or a security token, which are then compared against a trusted record. Strong authentication is crucial for protecting sensitive data and preventing unauthorized access to systems and networks. For instance, logging into your online banking portal requires authentication to ensure only you can view your financial information. This process is distinct from authorization, which determines what authenticated users are allowed to do. Concepts of authentication are fundamental to security domains covered in certifications like CompTIA Security+ and CISSP.