Around 2,000 years ago, the Roman general Julius Caesar needed to send secret messages to his commanders without his enemies reading them. So he used a simple trick. He took every letter in his message and shifted it three places forward in the alphabet. A became D, B became E, C became F, and so on. The whole message turned into gibberish.
It seems silly today, but it actually worked. Most people in ancient Rome couldn’t read at all, and the ones who could had probably never even imagined the idea of a secret code. If an enemy intercepted a Caesar message, they’d just stare at meaningless letters. Even spies took ages to figure it out.
Today the Caesar cipher is one of the easiest codes in the world to crack. There are only 25 possible shifts, so you can try every single one in a few seconds. But it inspired thousands of years of codemaking that led, eventually, to the unbreakable encryption that protects your messages and bank account online today.
