AJAX, conceived in 2005, has really transformed the web in major ways. It has helped websites evolve into Rich Internet Applications (RIAs) by allowing web pages to make direct requests to web servers without reloading the page. This is a crucial factor that enables rich user experience.
However the problem with AJAX is it is possible to create different custom functions to handle Ajax calls. This becomes a messy affair when a web application uses different types of Ajax calls.
jQuery has put all of the properties of Ajax into one simple API. You can control everything
including the url, cache, success function, data type, and even synchronization, all from one neat declaration.