This is a perfect coffee table book, to leave around and browse through from time to time.
I have to admit I didn't really read carefully all the text and information. I did look at all the illustrations though--everyone is sure to find something of interest, and also to learn or see something new. Actual ciphers and secret codes, language, writing, signing, signalling, magic, mysticism and religion, science and math, sociology, psychology, music, literature, art and war: all kinds of communication are covered.
Take a look and google away.