When animal communication involves multiple receivers, this may be referred to as an "audience". The study of animal communication is a rapidly growing area of study and plays an important part in the disciplines of animal behavior, sociobiology, neurobiology and animal cognition. Even in the 21st century, many prior understandings related to diverse fields such as personal symbolic name use, animal emotions, learning and animal sexual behavior, long thought to be well understood, have been revolutionized.
When the information sent from the sender to receiver is either an act or a structure that manipulates the behavior of the receiver, it is referred to as a "signal". Signalling theory predicts that for the signal to be maintained in the population, the receiver should in most cases receive some benefit from the interaction as well as the sender. Both the production of the signal from the sender and the perception and subsequent response from the receiver need to coevolve. It is important to study both the sender and receiver of the interaction, since the maintenance and persistence of the signal is dependent on the ability to both produce and recognize the signal. In many taxa, signals involve multiple mechanisms, i.e. multimodal signaling.