Firebase Authentication is a service provided by Firebase, a platform developed by Google that helps developers manage user authentication in their applications. It supports various sign-in methods, including email and password, phone number, and popular social media accounts like Google and Facebook. This flexibility allows users to choose their preferred way to log in, enhancing user experience. The service simplifies the process of securing user accounts by handling tasks such as password storage and verification. Additionally, Firebase Authentication integrates seamlessly with other Firebase services, making it easier for developers to build and maintain secure applications without extensive backend infrastructure.