Asynchronous Put the “A” in AJAX
The key word is asynchronous.
“1. A process in a multitasking system whose execution can proceed independently, “in the background”. Other processes may be started before the asynchronous process has finished.”—Dictionary.com
Most web pages are rather “choppy” because they need to “refresh” themselves, which is a nice way of saying completely re-load the entire page. This must happen every single time they need to “refresh” their data from the server. You probably have figured out by now that this takes time. What AJAX does is allow a web page to asynchronously update only the portion of the web page that is actually in need of fresh data instead of the entire page. Not only is it much faster, but the effect is that it is much smoother. This is because your eye does not have to endure the “flicker” or “hang ups” of the complete page re-load. Sometime the transaction is so smooth that the user often has no idea that it has happened. Knowing that you have affected the page is often important and a part of good usability. This has lead to coming up with ways to give the user a pleasant visual signal as feedback that they have caused a change on the page.
“A” is also for AND
“X” is for XML
The data that is passed back and forth between the server and client’s computer is very often XLM data. However this is not always the case. I very often pass simple text output by PHP code on the server. But anyway, the “X” is for XML.
The basic thing to know is that AJAX is in and of itself not a programming “language” per say. It is a technique or way of doing things that very nicely fits in with the Web 2.0 way of designing web sites. It helps to create a smoother faster more pleasant human experience when it is used properly. Ah! Yes, using it properly. There is a topic for several posts.