FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.7+ based on standard Python type hints. One of the key features of FastAPI is its automatic OpenAPI validation and documentation, which allows you to automatically generate interactive documentation for your API using Swagger UI. FastAPI is built on top of Starlette, which is a lightweight ASGI framework, and is designed to be easy to use and to scale.

To get started with FastAPI, you will need to install the FastAPI package using pip. You can then create a new FastAPI application by defining a Python function that takes in an FastAPI object and uses it to define your API endpoints.

Here is an example of a simple FastAPI application:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

This example defines a single endpoint at the root path (/) that returns a JSON object containing the message "Hello World".

To run this application, you can use the uvicorn ASGI server, which is automatically installed with FastAPI. Simply run the following command:

uvicorn main:app --reload

This will start the server and you should be able to access the endpoint at http://localhost:8000/.

FastAPI also includes support for dependency injection, which allows you to easily manage the dependencies of your application and make them available to your API functions. This can be particularly useful for managing database connections or other resources that you need to use in multiple places in your application.

I hope this gives you a good overview of FastAPI and how to get started with it.

Enjoy!