how does this welcome page work

[waloshin]

Everytime you refresh the page the background changes.

http://www.jeepz.com/

[FourCandles]

Not sure how technical an answer you're looking for?

Basically this page uses a script called rotate.php, which calls a random image from a set stored on the server each time the page is loaded.

Subtle difference in terminology, but it doesn't call a different image each time, just a random image. If you refresh a few times you'll notice that sometimes it calls the same image twice in a row.

This idea is far more widely used for random headers or banners; in fact I can't remember having seen a site using it for the whole background image before.