The HTTP method PATCH is used for partial updates of a resource on the server. This method allows the client to send only the part of the data that needs to be changed to the server, without sending the full volume of data, making it useful for efficiently updating large resources without the need for complete transmission.

For example, if you have a web application for managing a task list, and you need to change only the status of one task from "in progress" to "completed", you can use the PATCH method. Your client code will send to the server only the update for the "status" field with the value "completed", and the server will change only that part of the information on the server, without altering other data, which can reduce the amount of data transmitted and ease the processing of requests on the server.