Name for NextGen image view technology?

Hello-

I was curious what is the name of the “pop-up” technology that NextGen Gallery uses to display images an individual clicks? It is the same that Facebook uses for their galleries, where a thumbnail is clicked, and the image is displayed in the browser and the background is dimmed/put out of focus, and to close the image/return to the gallery a user either clicks a link or just to the side of the image?

Thanks!