"Pop-up ads or popups are a form of online
advertising on the World Wide Web intended to increase web traffic or capture
email addresses. It works when certain web sites open a new web browser window
to display advertisements. The pop-up window containing an advertisement is
usually generated by JavaScript, but can be generated by other means as
well.
A variation on the pop-up window is the pop-under advertisement, which
opens a new browser window hidden under the active window. Pop-unders do not
interrupt the user immediately and are not seen until the covering window is
closed, making it more difficult to determine which web site opened them." (Wikipedia.org)
Pop-Under
Ads
