AJAX stands for Asynchronous JavaScript and XML. It is a complete game changer when it comes to user experience. Normally, web pages are loaded one at a time. When a user wants more content, they click a link. With AJAX, a user can click something and content can be loaded into the page, using JavaScript, without reloading the entire page.
Essentially, the user does some event that fires off an AJAX HttpRequest after an XMLHttpRequest object has been created. The server then processes the HttpRequest, and returns the data back to the browser. Now without JavaScript, it would be entirely worthless unless you were posting data to a database. We will set up our AJAX so it calls a JavaScript function, known as a Callback Function, to use our returned data from the server in the next tutorial.
Why Use jQuery Instead?
Learning AJAX is a great feat for any developer, but when it comes to developing, it is usually best to keep it simple. jQuery already has methods of JavaScript functions that do almost everything AJAX can do. What’s the point in rewriting long code that is already available to you? There isn’t. So, if you really love the fundamental understanding of programming read the AJAX tutorials. If not, read the AJAX tutorial under jQuery.