What is AJAX?

AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.


Lets say a Live Music Promotor wanted to allow a potential clients to view information about all of the Bands that they had on their books.
They could list all the information on one page but that would make the page extremely large and quite slow to download. It would also be awkward for the user to navigate to the band they wanted information about, especially if the Promotor had hundreds of Bands.
They could also allow the user to click on a single Band from a list of normal HTML links. However, this would mean that the page would have to ask the webserver to send down a new page via the internet.

A better way would be to use AJAX...

Select a band from the drop down list


AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes.

This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.

Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.