Semaphore is similar to Morse code in that each letter of a message is translated into another form to allow it to be more easily communicated. While Morse code is used to send messages electronically over a telegraph line, semaphore is used to visually communicate information over long distances.
To use semaphore, an operator holds a flag or lighted wand in each hand. The operator extends their arms to the correct position and pauses for each letter of the message. "Attention" is the only signal that involves movement and the "rest" position is the only time when the flags should cross.