Secret messages are communications that are intentionally hidden or disguised to prevent unauthorized access. They can be created using various methods, such as codes, ciphers, or invisible ink. People often use secret messages for privacy, security, or fun, like in games or puzzles. Throughout history, secret messages have played a significant role in espionage and military operations. Famous examples include the use of the Enigma machine during World War II and the Caesar cipher, named after Julius Caesar, who used it to protect his messages. Today, digital encryption techniques are commonly used to secure online communications.