Semaphore is a means of communication using flags. It was especially used on ships throughout history as a visual means of communication between boats and between boats and the shore. Two flags would be held in different combinations and at different angles to the body in a set pattern to symbolize letters. This was a highly efficient form of visual telegraph. In addition to semaphore, other flag signals were used, simply by different images, colours, and shapes of flags. The French land semaphore system could send messages great distances in minutes. Stations were set up within sight of one anotehr, and a message would travel from station to station until it reached its ultimate destination. Obviously, some drawbacks to this system would have been the fact that messages could not be sent after dark, and that many signal stations were needed to send a message over any considerable distance.