What does the body of an HTTP request typically contain?

The body of an HTTP request typically contains the payload data, which is the main content being sent to the server. This payload can include various types of structured data such as JSON, XML, form data, or other formats depending on the application and API being used.

When a client makes a HTTP request that requires sending additional data to the server (like posting a form or uploading a file), that data is included in the body of the request. The body is separate from the request headers and the query string.

The query string, while part of the request, is typically included in the URL and is used to pass parameters to the server. In contrast, the payload data in the body is where the bulk of the data intended for processing resides. This distinction is crucial for understanding how client-server communication works in web applications.

The other options—secure tokens, response data, and error messages—do not belong in the body of an HTTP request. Secure tokens are usually included in headers for authentication. Response data comes from the server back to the client as part of an HTTP response. Error messages are generated by the server to inform the client of issues that occurred during processing and are also part of the response, not the initial request.