AJAX

Asynchronous JavaScript and XML(Ajax) is very similar to JavaScript. You need to understand HTML and JavaScript coding before you can learn Ajax. Ajax can be used to create better, more interactive and animated web pages. With Ajax, the JavaScript communicates directly with the server and therefore web pages do not need to reload every time an action is performed. Ajax can also be used to change only a section of the web page and leave the rest of the data as is. This also makes the website smaller and faster as only a fraction of the data is being changed.
When validating a form using JavaScript, the user clicks the submit button and the request is sent to the server; the user needs to wait for a response from the server, the web page is then reloaded with the new data. This is what makes Ajax faster and more convenient. It makes use of XMLHTTPRequest to communicate directly with the server, the web page is not reloaded and there is no waiting period for the response from the server.