Morse code
Morse code is an old system of encoding messages that is used to send telegraphic information using signals and rhythm. In written communication,  Morse code uses dots and dashes to represent a limited number of alphabet letters, numbers, punctuation and special characters of a given message. When messages are sent by sound, radio signals or light flashes, dots are short beeps or clicks or flashes, and dashes are longer ones. For example, Wikipedia written in Morse code is .-- .. -.- .. .--. . -.. .. .-