The Enigma machine is a cryptographic device that was originally developed in Germany after World War I for secure commercial and military communications. Comprising a keyboard, rotors, and a series of electrical circuits, the machine was designed to encrypt and decrypt messages by substituting letters according to a pre-determined but changeable set of rules. The device was best known for its use by Nazi Germany during World War II to encode military communications. The machine's cryptographic capabilities were considered very secure at the time, and it was a significant challenge for the Allies to break the code. However, through a concerted effort led by figures like British mathematician Alan Turing, the Allies were eventually able to decipher messages encrypted with the Enigma machine, giving them a critical advantage. The cracking of the Enigma code remains a landmark episode in the history of cryptography and is often cited as a pioneering moment in the development of modern computing.