Stenography was first used hundreds of years BC, and it was at about his time that cryptography was invented. As suggested earlier, it was much more powerful than stenography, since if the 'enemy' did intercept the message, they could not read it, and gained nothing from the interception except the possibility of preventing the intended recipient from receiving it. Enemy is a fair term - until recently, leading-edge cryptography has been used almost exclusively by the military, and by and governments, who could consider anyone wanting to read their secret messages the enemy.
Cryptography relies on two fundamental procedures, transposition and substitution. These two can be used together or alone; here is a description of each on its own: