JSON vs. XML: Browser security models. This gets into the cross-domain issue, which helped increase JSON's popularity. Before you jump in with "But, but…" let me finish the list.
You could use any of these formats with either the cross-domain solution, or using XMLHttpRequest. Yes, really,...
this tutorial will be about using the Mootools JS library with ajax, if you dont know a thing about ajax you will do just fine with mootools. but you need to have know some javascript to keep up.
Sun, Dec 20 | from Tutorialized.com