The HTTP method PUT is used to update an existing resource on the server or to create a new resource if it does not already exist. This method sends data to the server that replaces or updates the content of the specified resource according to the provided URL.

For example, if you have a web application for managing a to-do list and you want to change the name of one of the tasks from "Clean the house" to "Clean the room," you can use the PUT method. Your client code will send new data with the updated name to the server, and the server will replace the current information about this task with the new data. If such a task does not exist, the server may create a new resource with the specified data. Thus, the PUT method allows the client to update or create resources on the server.