AJAX is based on Internet standards

AJAX is based on the following web standards:
JavaScript
XML
HTML
CSS

AJAX is about better Internet-applications
Internet-applications have many benefits over desktop applications; they can reach a larger audience, they are easier to install and support, and easier to develop.
However, Internet-applications are not always as "rich" and user-friendly as traditional desktop applications.
With AJAX, Internet applications can be made richer and more user-friendly.

There is nothing new to learn.
AJAX is based on existing standards. These standards have been used by developers for several years.