What is AJAX?

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AJAX stands for Asynchronous JavaScript and XML. Many modern websites, big and small, implement this technology in many different ways, but what exactly is it? Here is an explanation in simple terms...

An AJAX application is a web page that functions more like a desktop application than a traditional web page in that it feels more responsive. It works by transferring small pieces of information in the background and updating just the affected area of the page without reloading the whole thing. This not only speeds up web applications and lowers bandwidth consumption, it also increases end-user enjoyability. As AJAX becomes more popular, the gap between the Internet and desktop applications will become increasingly smaller.

AJAX is actually a collection of technologies that work together. The main component that separates a regular web application from an AJAX enabled application is JavaScript, which provides the mechanism for sending and receiving data in the background. Additionally, AJAX can make use of CSS to stylize page components and change the appearance on the fly using JavaScript.

Most implementations also include server-side components such as PHP to dynamically processed the data sent to and from the server. Usually this also involves a database technology such as MySQL to store and retrieve data. In short, a typical AJAX application uses JavaScript, XHTML, CSS, a server-side programming language, a relational database, as well a data structure such as XML or JSON. All of these things must work together to create a website that rivals desktop applications in responsiveness, which is the goal of an AJAX developer.