Crafting JSON Requests

While GET requests are used to retrieve data, POST and PUT requests are used to send data to an API, either to create a new resource or update an existing one. This data is typically sent in the 'body' of the HTTP request, and the most common format for this payload is JSON. When sending a JSON payload, two things are crucial. First, the data itself must be a correctly formatted JSON string. In client-side code, like a Python script using the `requests` library, you would typically construct a dictionary and let the library handle the serialization into a JSON string. Second, you must set the `Content-Type` header of the request to `application/json`. This header tells the server what kind of data to expect in the request body so it can parse it correctly. If this header is missing or incorrect, the server might fail to understand the request, leading to a `400 Bad Request` or `415 Unsupported Media Type` error. The server-side application (e.g., one built with Flask or FastAPI) is then responsible for receiving this request, reading the `Content-Type` header, and using a JSON parser to deserialize the request body back into a native data structure (like a dictionary) that can be easily worked with. Properly crafting JSON requests is a fundamental skill for interacting with virtually any modern API that involves data creation or modification.