Authentication systems are processes that verify the identity of a user or device before granting access to resources. They typically require users to provide credentials, such as a password or biometric data, to confirm their identity. Common methods include username/password combinations, two-factor authentication, and biometric scans like fingerprints or facial recognition. These systems are essential for protecting sensitive information and ensuring that only authorized individuals can access certain data or services. By implementing robust authentication measures, organizations can reduce the risk of unauthorized access and enhance overall security for their digital environments.