What is AJAX and what does it have to do with my website?
The word AJAX is an acronym for Asynchronous JavaScript and XML. AJAX isn't a programming or scripting language it's simply a new way of doing things whereby your combine already existing technologies to make websites more user friendly and dynamic. The critical component of this is JavaSCript. JavaScript if you don't know already has very little to do with JAVA. Whenever I say something about JavaScript people instantly think I'm talking about Java. JavaScript is a client-side scripting language which means that it's a programming lanaguage which is run by the "client" or in this case the web browser. JavaScript is included with all modern web browsers (Mozilla Firefox, Internet Explorer, Opera, etc). It works just like HTML where it's simply text which is sent to the web browser, the web browser than processes this "text" on the clients computer which then converts the text into a web page for the viewer to, well...view. This is actually a nice feature since the processing is done by the web browser you don't have to re-send information in order to make changes to the web page (as is the case with say Perl or PHP based website scripting).
Now that you know the JavaScript part of AJAX let me explain another important part: XML. For those of you who don't know already XML is a standardized form method of formating data so that various programming languages, software applications, development tools, etc can all read each others output. Prior to XML everything was somewhat proprietary. There wasn't a standard way of taking the output from one application and importing it into another unless the development team behind the scenes specifically programmed that feature. But with XML this is not only possible but it's likely. Now you can take the output of just about any program in XML format and import it into just about anythign else.
AJAX combines standards with JavaScript in order to make websites more user friendly with interfaces which resemble using software instead of simply reading a book. Making web pages more interactive is the name of the game. We've all encountered it by now. A new fancy pop-up type menu which appears when you mouse-over a link. Or data that appear and disappears without having to submit the form. This can all be done with the AJAX technique.