A billboard (also called a hoarding in the UK and many other parts of the world) is a large
The largest ordinary-sized billboards are located primarily on major highways, expressways or principal arterials, and command high-density consumer exposure (mostly to vehicular traffic). These 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 mostly along primary and secondary arterial roads. Posters are a smaller format and are viewed principally by residents and commuter traffic, with some pedestrian exposure.
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 was the
The first "scented billboard", an outdoor sign emitting the odors of