FastAPI Basics

FastAPI is a modern, async-first Python web framework built on top of Starlette (the ASGI toolkit) and Pydantic (the validation library). It uses Python type hints to drive request validation, response serialization, and automatic OpenAPI documentation. This lesson covers what FastAPI is, how to write a hello-world endpoint, how path operations work, how Pydantic models shape requests and responses, dependency injection, async endpoints, and how FastAPI compares with Flask and Django.