Can you help me with this effect (a tutorial)

Hi folks. I once Knew a tutorial for this but can’t remember what the effect is called. It’s the one where you click on a thumbnail on an html page and it opens a large version with the rest of the screen blacked out.

example:
http://andrewshillito.com/blog/3d-design-2/honda/

I’d do a google search but don’ know what the effect is called.

thank you.

mr marley.