Configuration files are crucial in setting up and configuring an HTTP server. These files provide a roadmap for the server in terms of which ports to listen to, the server’s root directory, which files are executable, and which are not. They also indicate the server’s performance capabilities such as connection timeout limits, the number of threads that can process simultaneous requests, and the maximum size of client requests. With configuration files, system administrators can tweak server settings for various purposes such as performance optimization, security enhancement, or even to customize their HTTP server to meet specific needs.