Aimed at upper-level undergraduate and first year graduate students, this book covers all aspects of the subject from neurobiology and evolution to physics and economics. Starting with the physics and physiology of signal production, propagation and reception, the book proceeds to the economics of cooperating communicators and ends with a discussion of the complications arising when the interests of sender and receiver do not coincide. A variety of signal analysis and evolutionary methods are explained and demonstrated using examples. Although the authors emphasize a quantitative approach throughout, only a basic knowledge of algebra is needed and the relevance of all the results is explained. The authors also identify unresolved issues - subjects for future research.