CAPTCHA has become a popular means of securing forms against automated submission, by requiring users to enter a string displayed in an automatically generated image. This implementation uses Ajax to conveniently combine CAPTCHA into normal pre-submission form verification. You'll need PHP to be installed with the GD image library (most PHP implementations will have this as standard).

AJAX allows you to make a call to an http server (typically an RSS feed or a webpage), get it’s content and load them into your existing page without having to refresh the whole page. This means that services like email don’t have to reload the whole page everytime you click a message, saving on bandwidth (loading the header/footer all over again) and making things more efficient.

If you want to have live data on your website, that will change all on its own without you having to constantly refresh the page, then this tutorial will show you how to. Assumes you have an understanding of the AJAX (XMLHttpRequest) object.

Ever wanted to make your own "live" advanced search that gives you suggestions as you type. This tutorial will show you how to make one just like Google's new "Suggest" search feature.

This tutorial explains from the very beginning how to use AJAX in web applications. It is assumed you have a knowledge of Javascript (with a little DOM) as well as a server side scripting language, although you should pick it up easily.

This Ajax reader is written in JavaScript only. Itrequests a backend URL on the same server then displays the feed.

Step-by-step tutorial to understand the XMLHttpRequest object and how to use it from JavaScript. Examples with text, XML and JSON files. The tutorial is completed by demo pages that you can use as templates for you own website. Plus a specific JSON tutorial a very simple to use format.

With Head Rush Ajax, in no time you'll be writing JavaScript code that fires off asynchronous requests to web servers...and having fun doing it. By the time you've taken your dynamic HTML, XML, JSON, and DOM skills up a few notches, you'll have solved tons of puzzles, figured out how well snowboards sell in Vail.If you thought Ajax was rocket science, this book is for you. Head Rush Ajax puts dynamic, compelling experiences within reach for every web developer.

Thanks to Ajax, we can provide real-time feedback to the user using server-side validation scripts and eliminate the need for redundant validation functions without giving up a solution that degrades gracefully when JavaScript is disabled.

In this article, the first of three parts, you will start creating a simple web-based POP 3 client using Ajax, which will use "XMLHttpRequest" objects to retrieve messages from a mail server.