What is RESTful API design and how do you implement it in Node.js?

RESTful API design is an architectural style for building networked applications. It relies on standard HTTP methods (GET, POST, PUT, DELETE) to interact with resources identified by URLs. In Node.js, you implement RESTful APIs using Express.js, defining routes that correspond to these methods and resources. Proper status codes (200, 201, 400, 500, etc.) are also crucial.