- HTML (or XHTML) and CSS for presenting information
- The XMLHttpRequest object to exchange data asynchronously with the web server. (XML is commonly used, although any format will work, including preformatted HTML, plain text, JSON and even EBML)
Like DHTML, LAMP, or SPA, Ajax is not a technology in itself, but a term that refers to the use of a group of technologies together. In fact, derivative/composite technologies based substantially upon Ajax, such as AFLAX, are already appearing."
While somewhat complicated, AJAX is being used more and more by organizations to create web applications that operate and feel like fat client apps.
If this intrigues you and you want to learn more about AJAX, here are some resources to get started: