FastAPI is a modern, fast (high-performance) web framework for building APIs with Python 3.6+ based on standard Python type hints. It is designed to create RESTful APIs quickly and efficiently, leveraging the power of asynchronous programming to handle many requests simultaneously. FastAPI is built on top of Starlette for the web parts and Pydantic for the data parts, making it easy to validate and serialize data. One of the standout features of FastAPI is its automatic generation of interactive API documentation using tools like Swagger and ReDoc. This allows developers to test and explore their APIs directly from the browser, enhancing the development experience. FastAPI is particularly well-suited for building microservices and applications that require high performance and scalability.