"So what is Ajax, it stands for Asynchronous JavaScript and XML. For reference asynchronous literally means "not at the same time." Asynchronous events in programming are events that are happening independently to the main programming flow. Asynchronous actions are actions executed in non-blocking scheme, allowing the main program flow to continue processing (http://msdn2.microsoft.com/en-us/library/7ch3stsw.aspx).

Really Ajax is a technique of web development. In this technique you use JavaScript, XML, and optionally another scripting language such as PHP or ASP. Although there is an additive to this technique not mentioned. That additive is the ability to pass variables and data back to the server and then back to the viewer's Internet browser with out the view having to refresh the web page or visit another page.

Another thing one should immediately understand about Ajax is that you're not required to have the data in an XML format. This opens the door for using scripting languages like mentioned. To receive and send this data from other scripting languages or XML there is an object called XMLHttpRequest that is used. This object is called in JavaScript and is available to most web browsers.

There are many benefits to using Ajax. One is fewer loads on the server. With Ajax you can create web apps that don't have to require a large load of data being pulled off the server. Think about it, of course some images page and things are cached but there are times where it have objects that would not be pre-cached that could be saved by using Ajax.

Another benefit is you can pull retime data without refreshing and having the page flicker or waiting for page loads (the data load is all you wait for). This makes it easy to create web apps that deal with updating, editing, and adding data such as like with a database.

One other benefit is you can show the website viewer a loading message, image, or whatever you want. While your requests are being made in ajax you have have the ability to have somthing being show to the view as the requests are processing and then show your request on the screen.

And there are many other benefits, I could go on and on about what else you could use this for. If you want to get a quick easy free Ajax tutorial"