Enigma machine

An Enigma machine was a machine used in World War II by the German military to send secret messages. It used electric connections and rotating disks to turn words into secret codes that could not be understood without a special machine to decode them. In order to make the codes even harder to crack, the Enigma machine was designed so that the rules for how to make the codes changed every day. This way, only people with the special Enigma machine and knowledge of the changing rules could read the messages.