An advertisement on a website that is more like a TV commercial, which takes center stage. Meaning "in between," interstitial ads display in a separate window while you download the next Web page. Contrast with a banner ad, which is a more passive form of advertising. Introduced in 1997 by San Francisco-based Streamix, HyperStitial was software that resided in your computer and enabled your browser to display interstitial ads. See Superstitial.