How does Morse Code work? | Britannica

International Morse Code uses combinations of dots and short dashes for all letters. In addition, the International Morse Code uses dashes of constant length rather than the variable lengths used in the original Morse Code. For example, the universal distress signal “SOS” is communicated by three dots, three dashes, and three dots—three dots denoting the letter “S” and three dashes denoting the letter “O.”