User authentication is crucial for application development, especially when managing multiple related applications, where Single Sign-On (SSO) can simplify the login process by allowing users to access all applications with one set of credentials. This blog post explains how to implement SSO in WordPress using FusionAuth as the identity provider, which supports various programming languages and can be self-hosted on different operating systems. The tutorial guides users through setting up a WordPress instance with Docker, installing and configuring the OpenID Connect Generic plugin, and setting up FusionAuth to handle authentication, enabling users to log in with the same credentials across multiple applications. By integrating FusionAuth with WordPress, developers can streamline user management and enhance the user experience by reducing the need for multiple login details. The process includes configuring various endpoints for authentication and testing the setup to ensure users can log in and register seamlessly, with FusionAuth providing a customizable login interface that can be themed to match the application.