Authentication protocols are systems that verify the identity of users or devices before granting access to resources. They ensure that only authorized individuals can access sensitive information, such as personal data or financial records. Common examples of authentication protocols include OAuth, SAML, and Kerberos, each designed to provide secure methods for confirming identities. These protocols work by requiring users to provide specific credentials, such as passwords, biometric data, or security tokens. Once the credentials are verified, the user is granted access. This process helps protect against unauthorized access and ensures that data remains secure in various online environments, such as web applications and cloud services.