AJAX is a client/server system. It is a standard that is compatible with all versions of IE browsers, Mozilla/Firefox browsers, the Opera browser and some others. Any browsers that were released in the last few years will work. It uses a JavaScript object commonly referred to as the XMLHttpRequest object within the client-browser HTML page, though there are some variations of this object in MS Internet Explorer browsers. We will demonstrate a simple script that is compatible with all browsers. You use this XMLHttpRequest object to simply send a GET or POST request to a Form handling script on a server, then the server script returns a response to the browser XMLHttpRequest JavaScript object. This text response can be plain text, HTML text with all tags and images or an XML-structured document.