At first glance, the Enigma looks kind of like a typewriter, which in some sense it was, only weaponized. To send an encrypted message, you'd simply type it into the machine, which would then translate the letters into a "cipher-text" agents could pass along in secret. If you received an encrypted correspondence, you would simply type the strange "cipher-text" into the Enigma, and one by one, the decoded letters would light up on the screen until the real message appeared. While the most basic codes might swap all "A"s for "Bs," the Enigma had 17,000 different combinations, as "A"s could be "B"s, "M"s, "Z"s, or any letter, all in the same message, depending on the combination of letters that preceded it. And it did it all automatically.