1. Steganography
Steganography is the art and science of writing hidden messages in such a way that no one apart from the sender and intended recipient even realizes there is a hidden message (Wikipedia, the free encyclopedia)
Like encryption, steganography involves the securing of information through the manipulation of data [1]
By contrast, cryptography obscures the meaning of a message, but it does not conceal the fact that there is a message (Wikipedia). Steganography is designed to hide the data from the view [1]
Steganography is the science of hiding information. Whereas the goal of cryptography is to make data unreadable by a third party, the goal of steganography is to hide the data from a third party (Garry C. Kessler) [2]

2. History
The word steganography is of Greek origin and means "covered, or hidden writing".
The term steganography was introduced at the end of the 15th century
The use of steganography dates back several millennia.
In ancient times, messages were hidden on the back of wax writing tables, written on the stomachs of rabbits, or tattooed on the bald head of soldiers

3. Steganographic Message
Steganographic Message has three parts:
container or carrier: the file which conceals data
hidden message: the actual data
steganography key: could be the hidden message was also encrypted, or the key was used for the steganography method

4. References
1. Marjie T. Britz, Computer Forensics and Cyber Crime, An Introduction 2. 3.