Normally when we use post method with forms, the requests are geting cached. I mean when we use the back button to visit the previous page the request is not being sent to the server to display the previous form. It just loads the form from the cache and loads the field values from the cache. But it is not the case with ajax. when we use ajax with post method the requests are not cached. when we use the back button also the ajax gets the content from the server which is contrary to its "get" method. So why this difference?