This document provides instructions for creating a RESTful API in PHP. It includes code for a PHP class called API that establishes a database connection and defines methods for common API functions like login, getting a list of users, and deleting a user. The code uses the REQUEST_URI to dynamically call the corresponding method. Additional details are provided on authentication, returning JSON responses, and URL rewriting for friendly URLs. Comments discuss topics like validating request methods, handling errors, and extending the API with features like authentication.