Uses Semaphore is a term used to describe the use of semaphore signals for communication. Semaphore signals are visual signals used to communicate messages over long distances. They involve the use of flags, lights, or other visual indicators to convey information. The signals can be used to send messages between two people, or to send messages over a large area. Semaphore signals have been used since the 18th century and are still used today in some parts of the world.