A billboard is a large outdoor advertising structure (a billing board), typically found in high traffic areas such as alongside busy roads. Billboards present large advertisements to passing pedestrians and drivers. Typically showing large, ostensibly witty slogans, and distinctive visuals, billboards are highly visible in the top designated market areas. Bulletins are the largest, most impactful standard-size billboards. Located primarily on major highways, expressways or principal arterials, they command high-density consumer exposure (mostly to vehicular traffic). Bulletins afford greatest visibility due not only to their size, but because they allow creative "customizing" through extensions and embellishments.

Posters are the other common form of billboard advertising, located chiefly in commercial and industrial areas on primary and secondary arterial roads. Posters are a smaller format than bulletins and are viewed principally by residents and commuter traffic, with some pedestrian exposure.

Advertising style

Billboard advertisements are designed to catch a person's attention and create a memorable impression very quickly, leaving the reader thinking about the advertisement after they have driven past it. They have to be readable in a very short time because they are usually read while being passed at high speeds. Thus there are usually only a few words, in large print, and a humorous or arresting image in brilliant color.

Some billboard designs spill outside the actual space given to them by the billboard, with parts of figures hanging off the billboard edges or jutting out of the billboard in three dimensions. An example in the United States around the turn of the 21st century were the Chick-fil-A billboards (a chicken sandwich fast food chain), which had three-dimensional cow figures in the act of painting the billboards with misspelled anti-beef slogans such as "frendz don't let frendz eat beef."

Placement of billboards

Some of the most noticeable and prominent places billboards are situated alongside highways; since passing drivers typically have little to occupy their attention, the impact of the billboard is greater. Billboards are often drivers' primary way of finding out where food and fuel are available when driving on unfamiliar highways. There were approximately 450,000 billboards on United States highways as of 1991. Somewhere between 5,000 and 15,000 are erected each year. In Europe billboards are a major component and source of income in urban street furniture concepts.

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These sort of multi-sign advertisements are no longer common, though they are not extinct. One example, advertising for the NCAA, depicts a basketball player aiming a shot on one billboard; on the next one, 90 yards (82 meters) away, is the basket. Another example is the numerous billboards that advertise the roadside attraction South of the Border near Dillon, SC. They stretch along I-95 for many states.