A promise about future value. You can attach callbacks to it to get that value. The promise was "given" to you and you are the receiver of the future value. If we request a resource from another website, the result of a long calculation either from server or from a JavaScript function, or the response of a REST service, and we perform other tasks while we await the result. When the latter becomes available (the promise is resolved/fulfilled) or the request has failed (the promise is failed/rejected), we act accordingly. In Jquery, $.ajax, .fadeOut().promise(),  .fadeIn().promise() returns promise objects.