What is the main function of the PUT HTTP method?

The main function of the PUT HTTP method is to replace all current representations of a resource with uploaded content. When using the PUT method, the client sends a request to the server containing the data that should completely update the specified resource. If the resource does not exist, a successful PUT request can create a new resource at the provided URI, though its primary role is focused on updating existing resources.

This behavior aligns with RESTful principles, where a PUT is intended for idempotent operations; this means that multiple identical requests should have the same effect as a single request. Consequently, you can expect that the resource will be updated to match exactly what is sent in the PUT request each time it is called.

Other choices focus on different HTTP functionalities. Sending data to create a new resource is more closely associated with the POST method, which is used for creating resources and may result in new identifiers being assigned. Retrieving representations of a target resource corresponds to the GET method, which is specifically designed for fetching data. Lastly, fetching data without modifying resources also pertains to the GET method, as it is used to obtain data while ensuring no changes are made to the targets. Therefore, option C accurately encapsulates the PUT method's fundamental purpose within HTTP.