An online ad that appears in a pop-upbrowser window while the primary Web page is still loading. The word "interstitial" literally means "a small space in between things," which is how these ads appear, as mini-browsers, either on top of or behind your activescreen. They are likely to contain large graphics, streaming media, or applets, elements that regular ad banners don't usually have, due to size restrictions. Some studies say that more usersclick on interstitials than on ad banners. However, popular opinion indicates that users do not like interstitials because they slow down access to destination pages, they launch another browser (thereby slowing your computer down), and they are intrusive (most people don't appreciate having a window suddenly appear on their screen without their permission).