Morse code

original source
This ↑ is Morse code. Morse code was a very old, (about 160 years old) it was used as a method of communication during the war. People spent a long time learning how to listen to and send messages via a Morse code machine. Essentially its just beeps to any spy who didn't know Morse code, proving to be useful. Another useful thing about Morse code is that it was invented before the telephone had gone big and had a very large range ( useful for ships and air-crafts.) Now a day the Morse code is almost dead, only being used by some parts of armies and Morse code fanatics, otherwise most people don't use it.

Want to write your own Morse code but too lazy to go letter by letter following the graph? Luckily for you their are websites that let you write and listen to your own messages.
Like this one for example:
online Morse code

Fun test: try and decode my message↓
.. / .-.. .. -.- . / ..- ... .. -. --. / -- --- .-. ... . / -.-. --- -.. .