2.  AJAX – Asynchronous JavaScript and XML

3.  Ajax is used to develop fast dynamic web applications  Allows web pages to be updated asynchronously by transferring data server side behind the scenes  Ajax is not a programming language itself but uses various web development techniques such as JavaScript, PHP, HTML, CSS and XML

4.  Ajax uses HTTP requests to serve as the connection between the server and the user  Data is sent to the server, processed and immediately sent back to client side

6.  Similar execution to traditional Ajax but uses an XMLHttpRequest object  Instead of using a continuous HTTP connection, after a request is sent, the request is terminated, so there are new requests after each response

8.  Using HTML, JavaScript and PHP, we are creating a simple web page that displays 5 options of colors in which the user can change the background to their desired color

11.  JavaScript for UI //Function that is called by the forms in javascript function blue() { document.bgColor = "blue"; } //Form for calling a specific color

12. function blue() { var xhr; //try and catch block for particular web browser try { xhr = new ActiveXObject('Msxml2.XMLHTTP'); } catch (e) { try { xhr = new ActiveXObject('Microsoft.XMLHTTP'); } catch (e2) { try { xhr = new XMLHttpRequest();//Instantiates new XmlHttpRequest Object } catch (e3) { xhr = false; } } xhr.onreadystatechange = function() { if(xhr.readyState == 4) { if(xhr.status == 200) document.bgColor = "blue"; else document.ajax.dyn="Error code " ; } }; XMLHttpRequest object

13.  Ajax is effective for fast dynamic web browsing, it is commonly used so that a user does not have to refresh the we browser to acquire new information

14.  Ajax is commonly seen in the popular social network facebook  It is also used in eCommerce websites such as eBay  Most recent it is seen in Youtube