So what exactly does Ajax do. In a few words it saves time. Instead of the whole web page being sent back to the web server, where ever it is located. Only the section of the web page that needs updating is returned. Result no flash on the screen as the page is refreshed, just the instant change of whatever section of the web page was sent back to be refreshed. See the diagram above. The user on the web page calls for new information, the web page makes a call to a Javascript function. This in turn calls a PHP script which makes a call to the database for the information which is then sent back to then web page. Result a much cleaner method of development for the web and essential for eCommerce.