From the time of the Roman Emperors commercial businesses have used signs outside to tell the public about the business inside. Until the 20th century a sign was a message carved or painted on a piece of wood. As new technology became available, signs took on a new look.
During the last decade a completely new form of sign has become available. Now the message on the sign can change without changing the sign itself. This new sign displays digitally created words and images controlled by a computer or by a DVD player connected to the display.