Fundamentally, AJAX (Asynchronous JavaScript and XML) enables back-channel communication in Web applications so that only small portions of Web pages need to be updated in response to user activity.

New JSF 2.3 API enhances Ajax support In terms of JavaScript support, the new JSF 2.3 tag commandScript maps a client-side JavaScript method referenced in an HTML element to a corresponding method on ...

The problem with JavaScript/AJAX/Web 2.0 security flaws is that there has been no strong message going out to software developers regarding security being their responsibility, Chess said.

In addition, this means, Google is better at seeing the content behind more of your JavaScript or AJAX. Postscript: Google now has an official blog post up with more details.