Used by the ancient Egyptians, hiding the true nature of transmitted communications has a history going back thousands of years. In more modern times, a famous example is the Enigma machines used by the Germans in the Second World War. Today, encryption is a standard practice for protecting transmissions over the internet or any other networks, essentially using the same practices of converting messages into a secret code which can only be decrypted (and understood) by those with the corresponding key. Encrypted data is called ciphertext, while unencrypted data is called plaintext.