What are RESTful APIs, and how do you design a RESTful API using Node.js?

RESTful APIs (Representational State Transfer) follow architectural principles for building scalable and maintainable web services. Design involves using standard HTTP methods (GET, POST, PUT, DELETE) to interact with resources identified by URLs. Node.js can build RESTful APIs using Express.js, defining routes for each resource, handling HTTP requests with appropriate methods, and returning JSON responses.