Steganography is the practice of hiding a message inside a nonsecret message. It is not to be confused with stenography, the practice of taking diction, like a court reporter who transcribes the spoken words during a trial. Steganography goes back in history a long time, and an old-fashioned example is sewing in morse code messages in the stitching of clothing items.
In the digital world, people can hide any type of binary data inside an image, audio, or video file. The quality of the original may or may not suffer from this process. Some images can maintain their original integrity fully, but they have extra data hidden from plain sight in the form of a .zip or .rar archive. Some steganography algorithms are complex and hide the original binary data in the single lowest bit of each byte, only denigrating the original quality slightly. Other steganography algorithms...