WebAuthn is a web standard for secure authentication that allows users to authenticate to websites and services without the need for a password. It uses public-key cryptography, biometric data, or physical security keys to prove identity, offering enhanced security, passwordless authentication, resistance to credential stuffing and brute force attacks, improved user experience, widespread support, but also challenges such as compatibility issues, user experience limitations, security key availability, backup and recovery concerns, privacy worries, adoption difficulties, and complexity for developers. Implementing WebAuthn requires a server library, user registration flow, and client-side authentication using the Web Authentication API. To ensure a smooth user experience, it is essential to provide fallback mechanisms, secure connections, verify data properly, consider backup methods, test compatibility, and simplify the implementation through third-party services like WorkOS.