HV HTTP Multipart is designed to compose and serve multiple pages that replace each other in a single HTTP request. It uses the MIME content type multipart/x-mixed-replace content type to keep the connection open. It only works in browsers that support that content type, obviously. It can send multiple pages that replace each other even with different content types. It can iterate over a set of pages that are deliver one after the other waiting a given interval period. It can be used to show the progress of lengthy tasks or exhibit animations and slideshows.