What is the AJAX ? | Introduction

AJAX Stand for Asynchronous JavaScript And XML. It is a Technique which we request data from remote server without reloading entire page. AJAX is not a programming language rather then AJAX is a technique used by web developer in order to make website behave like desktop application.

AJAX is a technique not a programming language.

What technique comes in AJAX ?

•  HTML
• CSS
• JavaScript
• XML
• JSON (JavaScript Object Notation) :
• XML provides the capability to display data because it is a markup language. JSON files are more human readable than XML. JSON supports only text and number data type. ... Moreover, XML offeres options for transferring the format or structure of the data with actual data.
• PHP

What is Asynchronous in AJAX ?

Asynchronous means we are exchanging data to/from the server in the background without having to refresh the page.

e.g. Standard Client Server Application

If you consider Standard Client Server Application.

Client - Request to Server

Server - Response from Server

These are Standard Client Server Application where client has to wait for the response from the server to exchange other tasks on the web page.

The Major advantages of AJAX,

multiple request are happening concurrently in the same time or client doesn't have to wait for a response from a server in order to make a new request that main advantages of AJAX.

What about the request in AJAX are handled in the from of callBacks ? 

A CallBack is spacial function which is used in AJAX so that server can respond  to the client when it is ready to send data to the client.