How do they do that? Transparent foreground on a web page

Question

You know how sometimes you are on a good site and you click a button (like to submit a form) and the form doesn't go away, instead, the foreground becomes transparent and it contains a message of some kind, or another page. The message is at the forefront but the previous page is still mostly visible behind it - how do they do that? I'm assuming it's an Ajax-esque trick.

Answer 1

One way is to use GreyBox. I think this similar to the effect that you're talking about.

Answer 2

This is called a light box modal. There are quite a few JS plugins that can do this including Lightbox and the JQuery UI Dialog to name a couple. I just recently started using Fancybox and have been very impressed with its speed and configurability.

Here is a pretty good (not all inclusive) list of them:

http://spoonfedproject.com/jquery/extensive-list-of-jquery-lightbox-modal-plugins/