pop-down banner
A pop-down banner is a special banner that hides behind web pages. Viewers of the web page are unaware of the existence of a pop-down banner, which is located under the browser window and appears only when they leave the web page. Pop-down banners are the last banners to appear after closing all browser windows.They can have standard sizes of 140 x 180 pixels or 200 x 300 pixels, but so can a large format. Pop-down banners can be removed only by clicking them away.