When we send a request to the server , we expect a response. When we make an Ajax call to server with the help of XMLHttpRequest ,we have an option to get the response in many different formats. It can be a plain text , CSV(comma separated) , Xml etc. If the return data is in complex form or in a form of an object you need something called JSON. This post would give you a start up confidence to use JSON.

Ajax is nothing but getting the XMLHttpRequest and work on it to get or post data. Forming an XMLHttpRequest varies form browser to browser. This post shows , how to construct XMLHttpRequest object seamlessly.