Quote:
Originally Posted by greygoose11
What's a pop-under?  |
"A type of window that appears behind the browser window of a Web site that a user has visited. In contrast to a pop-up ad, which appears over (on top of) the browser window, a pop-under is less obtrusive as it hides behind other windows. Pop-unders are used extensively in advertising on the Web, though advertising is not the only application for pop-under windows."
For more technical details, spend some time with Almighty Google and Co.