There are many types of billboards, all of which are used all over the world. There are traditional billboards, digital billboards, mechanical billboards, and mobile billboards. Each one has a unique way of advertising their product or person. Billboards are especially popular because they can be custom designed to the buyer's specifications. Sizes of billboards vary, but typically run about 14 feet high and 48 feet wide. This size can vary greatly, however, due to many different factors. Billboards are popular because of the large lettering used on them, making them nearly impossible to miss.