The document defines various forms of television, radio, and digital advertising. It provides key statistics about television such as 99% of U.S. households having at least one TV and over 50% of ad spending going to TV. It also defines common TV and radio metrics and dayparts. Finally, it outlines different types of digital ads such as banner, rich media, video, and search engine marketing, and notes that online ad spending is second only to television in the U.S.