Creating means of secret communication where the existence of the message is not known to others and is unlikely to be discovered. It can be more useful than regular encryption, as an encrypted message is suspicious even if a person does not know what it says. If the person wasn't even aware that there was a message at all, it can be much safer for the communicators. Often a message will undergo both steganography and encryption for maximum security.

It was famously used by Jeremiah Denton, an American POW in Vietnam, who blinked the word 'torture' in Morse code during a press conference where he was being forced to state that he was being treated well.

Other examples include hiding secret images in the lowest bits of noisy sound files, writing in invisible ink on the back of a more innocuous letter, or encoding a message in the delays between a target computer receiving packets of data.