In code, each word in the message is replaced by a code word or symbol, whereas in cipher, each letter is replaced with another cipher letter or symbol. Ancient languages and scripts were understood using decoding and deciphering techniques.

Since antiquity, mankind has used some form of cipher to encrypt and protect messages. Here are 11 of the most important.

We've rounded up 15 of the most intriguing and enigmatic codes and ciphers from around the world. Some have already been cracked, while others still baffle the brightest minds. Come along as we explore this captivating collection and see if you have what it takes to crack them.

Zodiac Killer ciphers Partially solved (2 out of the 4 ciphertexts solved between 1969 and 2020) 1977 The Magic Words are Squeamish Ossifrage: Solved in 1993–1994 1983 Decipher: Solved [1] 1986 Decipher II: Partially solved (all 4 ciphertexts solved between 1985 and 1986, but the solution to the 4th ciphertext has since been lost) [2]

A code is where each word in a message is replaced with a code word or symbol, whereas a cipher is where each letter in a message is replaced with a cipher letter or symbol. In fact, when most people say "code", they are actually referring to ciphers.