To build a RESTful API, you should follow these basic steps: Plan and define API resources and their relationships, choose an appropriate technology and framework to build the API, implement standardized HTTP methods (GET, POST, PUT, DELETE) to interact with the resources, use the correct URI structure to identify resources, handle and return appropriate HTTP status and error messages, implement security and authentication, such as API keys or OAuth, optimizing performance, for example by using caching and pagination, document the API thoroughly so that it is easy for other developers to use and understand, test the API thoroughly to ensure that it works properly and meets the requirements, and monitor and maintain the API after launch to resolve any issues and improve performance over time.