Steganography is the hidden storage or transmission of information in a carrier medium (container). The word can be traced back to the Greek words components στεγανός steganós ‘covered’ and γράφειν gráphein ‘to write’, thus literally means “to write covered” or “secret writing”.
The modified medium is called a steganogram.
Information is hidden in such a way that a third party does not suspect anything when looking at the medium. This also ensures that the hidden information does not become known to third parties, i.e., secrecy is guaranteed (as in cryptography).
A cipher that uses this method is, for example, the Bacon cipher.