Semaphore is a flag signaling systems. In this system the letters of the alphabet are signaled by waving a pair of hand-held flags in a particular pattern. The flags are usually square. They are red and yellow in colour and divided diagonally with the red portion on top. The flags are held, arms extended, in various positions representing each of the letters of the alphabet. The pattern resembles a clock face divided into eight positions. Numbers are shown by special signals. Semaphore signals were used to exchange messages between other, but could see each other, but could not hear each other. They were used by railways to communicate with train drivers. Semaphore signals have generally given way to color light signals although there are still many places where semaphore signaling is in use.
