What is Ajax

AJAX stands for Asynchronous JavaScript and XML.AJAX is not a New Technology. it's a New way of combining existing technologies. What we do in AJAX is create the Asyncronous request to webserver using javascript and xmlhttprequest object and map a function to be excuted when the response is received. Asyncronous means the browser does not wait for server response after sending the request to server.The core component in AJAX is the XMLHTTPRequest object.
xmlhttprequest:-
its used to send request to, and receive the request from webserver.Using this object the webpage can make a request to the webserver asyncronously, and receive the response asycronously. Even though this object is not a w3c standards.