Semaphore is a communications system that involves visual signals by the means of the position of flags, rods, paddles or even bare or gloved hands. Flag semaphore uses custom mini flags on short poles. This method of communication is for distance communication, such as from one boat to another. This method of communication started in the 19th century and was most often used in the navy.

In modern flag semaphore the custom mini flags used are the “Papa” or white and blue flag, while at sea it uses the “Oscar”” or red and yellow flags. The signalman holds one flag in each hand, and the arms can extend in eight possible directions, spelling out the different letters of the alphabet and numbers. The custom mini flags used accentuate the arm positions, and the same result can be achieved by paddles or glow rods, commonly used at night.

The Japanese also have developed their own method of flag semaphore, with the custom mini flags are a solid white square for the left and a solid red one for the right. Unlike the flag semaphore using Latin letters, in Japanese semaphore the custom mini flags are moved to represent the brushstrokes of the Japanese alphabet or the katakana.

Though modern technology has given the world diverse forms of communications, flag semaphore still remains in use. Flag semaphore is used also in the mountains, where oral or electronic communication can be hard to come by. Lifeguards in some beaches also use the custom mini flags to communicate between lifeguard towers.