Codes and ciphers have been used for thousands of years to send secret messages. Historians believe that the first cipher or code was chiseled into a tomb in Egypt in the year 1900 B.C.E. Codes and ciphers use techniques that scramble words to make them difficult to understand. This is called encryption. Codes replace words or phrases in a message with another word, phrase or series of symbols. Pig Latin is one example of a code. Ciphers, like Morse code, replace every letter in a message with another letter or a symbol.
Cryptography, the study of encoding or scrambling messages is commonly used during wartime. Julius Caesar developed a cipher system to ensure that messages he sent to his troops could not be read if they fell into enemy hands. Codes and Ciphers were used during the Revolutionary War, and the telegraph was one of the most popular ciphers used during the Civil War.
Before the telegraph, secret messages were sent through visual codes, like semaphore, which is a system that uses the position of two flags to represent letters. Another way that communication was transmitted visually was through smoke signals, which Native Americans used as codes. During World War II, spoken codes were transmitted over wireless radio by Native Americans whom the Marines recruited as Navajo Code Talkers. The U. S. Military needed a code which enemy code breakers could not figure out. Codes based on the Navajo language were used because the Navajo language is hard to master even by people who speak other Native American languages. Their codes were never broken and The Navajo Code Talkers helped win the battle at Iwo Jima.