GET requests retrieve data from an API; POST requests send data to create or update resources. POST requests include data in the request body (often JSON), which the API processes. The API then typically returns a response, e.g., confirmation of successful creation. This segment clearly explains the fundamental difference between GET and POST HTTP requests using a visual diagram. It highlights that GET requests retrieve data from the server, while POST requests send data to the server for actions like creating new resources (e.g., creating a social media post). The explanation is concise and easy to understand, making it valuable for beginners learning about API interactions. This segment demonstrates how to send data within the body of a POST request using Postman, focusing on JSON format. It shows how to structure the JSON payload and then explains how to extract this data within the FastAPI path operation function using the `body` parameter. This practical demonstration is crucial for understanding how to handle data exchange in a real-world API scenario.