Steganography is the ancient practice of stashing secret text, images, or messages inside a different text, image, or message. It dates back to as early as the fifth century BC, when Spartan King ...
For most people, steganography is overkill. If you do need it, though, OpenPuff is the way to go. Steganography, or hiding messages in plain sight, is a storied practice dating back to ancient Greece.