Steganography

Here is what steganography is:  http://en.wikipedia.org/wiki/Steganography

Here is how it is said:  http://www.merriam-webster.com/dictionary/steganography

Here is some software for doing it:  http://www.cotse.com/tools/stega.htm

Here is why it is important:  http://gcn.com/articles/2010/07/01/russian-spies-undone-by-technology-problems.aspx?s=gcndaily_120710