interstitial
A Web page not requested by a user, usually containing an advertisement, that appears on the user's screen, often in an automatically opened new browser, when the user has clicked on a link to move from one Web page to another. The page that the user originally requested continues to load and the interstitial is programmed to disappear after a few seconds or when the user clicks on it to acknowledge having seen it. Interstitials are interruptive, like television advertising, rather than passive, like Web banner advertising.