Out-of-home advertising, therefore, is focused on marketing to consumers when they are 'on the go' in public places, in-transit, waiting (such as in a medical office) and/or in specific commercial locations (such as in a retail venue). Billboard advertising is a traditional out-of-home advertising medium, but there has been significant growth in digital out-of-home advertising in recent years. "Ad spending on these media [in the US] soared 27% in 2006 to $1.69 billion, with accelerated 28% growth expected in 2007," according to industry analyst firm PQ Media.
Two of the major US industry associations in this space include the much-older Outdoor Advertising Association of America, which covers a broad range of traditional and digital/alternative advertising, and the more-recent Out-of-home Video Advertising Bureau, which is focused on video/digital networks that combine content and advertising.
A more-recent concept that is gaining traction is that of 'place-based media' -- i.e., the concept of a media channel delivered in a specific environment. This term (sometimes also associated with the concept of 'alternative media') has been used by marketing research organizations, such as GfK, and media organizations covering this market segment, including MediaWeek, which has a place-based news channel. Place-based media is perhaps best construed to be a segment of the larger out-of-home advertising market, but one difference is that place-based media seeks to deliver both content and advertising in a singular, sponsored 'channel,' whereas out-of-home advertising may not necessarily carry content.