The article’s attempt to brand the approach with a catchy acronym is unfortunate. I agree with saladwithsteve, who writes
Nevertheless, the article is a nice introduction to XMLHttpRequest for non-technical audience (a better article for people who code is here.)
1)Getting new data from the server without going reloading the user interface: XMLHttpRequest is, as Garrett writes, a key part of the puzzle, since it provides a transport mechanism for data to be fetched from the server without refreshing the page.
2)Animation: Using CSS to position screen elements allows the ability to do animation / drag-and-drop. Animations are particularly important for screen transitions.