The main features of a RESTful API include stateless communication, resource-based interactions, and the use of standard HTTP methods (GET, POST, PUT, DELETE). RESTful APIs operate on the representational state transfer architecture, allowing clients to request and manipulate resources through URLs. They return data typically in JSON or XML formats, promoting simplicity and scalability. REST APIs are commonly used due to their flexibility, ease of integration, and compatibility with various platforms, making them a preferred choice in modern web development.