The current volume will emphasize uses, purposes, origins, and consequences of nonverbal communication in the lives of individuals, dyads, and groups-in other words, the behavior of human beings. As such, it will not emphasize communication systems per se nor the impact on humans of the physical environment, whether built or natural. With a field as widely represented as this one, full coverage within one volume is impossible. Therefore, the decision was made by the volume Editors to cover many different topics, the volume's unity will derive from its focus on the persons (or, in one chapter, non-human animals) engaging in nonverbal communication and the communicative and psychological aspects of this behavior. Nonverbal behavior is the more inclusive category and includes all emitted nonverbal behavior that may be subject to interpretation by others, whether the behavior is intentionally produced or not. In contrast, nonverbal communication refers to a subset of nonverbal behavior that represents a more active process whereby encoder (expressor) and decoder (recipient) emit and interpret behaviors according to a shared meaning code.