Authentication services 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 or perform specific actions. Common methods include passwords, biometrics, and security tokens. These services play a crucial role in cybersecurity by protecting data and preventing unauthorized access. They are widely used in various applications, such as online banking, social media, and corporate networks, to maintain the integrity and confidentiality of user information and transactions.