What is it? Ajax is a buzzword that describes a collection of Web-oriented programming technologies—all of them several years old—for creating Web applications that behave more like traditional computer programs.
What does it do? A Web application built with Ajax efficiently delivers additional information to a browser when someone clicks on a button or moves the mouse cursor over a part of the page, without refreshing the entire page. That, ideally, results in Web pages that respond almost as if they were a locally installed program. For example, a video rental company uses Ajax to automatically pop up a movie’s synopsis, complete with a thumbnail image of the movie poster, when a customer moves a cursor over titles in a list of search results. Previously, the site required loading to a brand-new page if a user wanted to find out more about a movie.