AJAX (Asynchronous JavaScript and XML provides much more than a simple programming language. It consists of a group of techniques to develop interactive web applications.
By using Ajax Web Applications the client-PC gets data asynchronously from the server without the need of reloading the current page. Receiving of the data occurs in the background and invisible to the user. More and more webpages use Ajax and this technique led to a lot of interactive animations and much better usability on websites.
Despite the name it is not really necessary to use the JavaScript programming language.
Even the use of data abstraction via XML is not mandatory.
In fact, even the asynchronous data request must not be made. Most data is requested via the XMLHttpRequest object or by remote scripts in case that browsers do not support the object
The term "Ajax" itself was created in 2005 but imilar techniques to request data asynchronously where already present since 1995. Java applets for example with the first version of the Java language where able to communicate with the server asynchronously after the webpage was completely loaded.
In 1996 the Internet Explorer presented the new HTML-element IFrame and this element showed a similar behaviour.
Finally in 1999 Microsoft created the XMLHttpRequest object in the ActiveX control for Internet Explorer 5. A short time later the developers of Mozilla and Safari countered with corresponding implementations. A standardization of the different implementations was made by the World Wide Web Consortium (W3C) on 5th April 2006 when it published the first draft of the specification of a corresponding object with the purpose to create a Web-wide standard to ensure the uniform conduct of websites even when using different browsers and operating systems.
Benefits of Ajax are in particular the simplification of data intensive Web sites where many pages are structured similarly.
The user experience is enhanced by the fact that there is no need to wait for a page-reload. Even the the Web server has less work to do since there is no need to generate und send the same complete page over and over again. Only small parts are needed. The parts that are actually changing.