1. What is Ajax?
Ajax stands for Asynchronous Java and XML. It is a set of client side technologies that allows asynchronous communication between client and server.
In synchronous communication complete round trip is performed with each Request/Response every time even when a small portion of data is to be refreshed. Ajax solves this problem of making a complete round trip to the server by making asynchronous calls
XMLHttpRequest is the basic fundamental behind Ajax which allows browser to communicate with web server without making post back