What is: AJAX
How To Use AJAX In WordPress
Normally, a web page must be refreshed to view new information. For example, when you fill out an online form such as a credit card purchase online, some sites need you to click next to let you know if you filled out something incorrectly. However, with Ajax, not only can the form let you know if you filled out something incorrectly, but it can also let you know if you’ve already made a previous purchase, or if your credit card was expired. Another example of useful Ajax is viewing online maps. Before Ajax, Google Maps required you to click the arrows to navigate their maps, and the page had to reload in order to see the new portion of the map you were interested in. However, Google Maps now utilizes the power of Ajax to fetch the new portions of the map and “redraw” the page where the map moves.