The winker alphabet (semaphore) is used for optical message transmission between ships or on land. With the development of voice radio, it lost much of its importance, but is still used today at sea, especially for military purposes.
In the winker alphabet, the individual letters of the Latin alphabet are described by the position in which the winker holds two flags. The flags are usually square and either diagonally divided yellow-red (flag Oscar) or red flags containing a smaller centered white square (obsolete).
Numbers are announced by the “number-follow” signal and correspond to the first ten letters of the alphabet, Alfa (=1) to Kilo (=0) without Juliett. The number ends with the next “interrupt” signal. The “Charlie” and “Echo” signals also serve as answer and error signs.
In addition to the well-known winker alphabet, there were various predecessors, including the wig-wag developed by Albert J. Myer in 1860 during the American Civil War with only one signal flag.