A "communication theory" is an attempted explanation of how and why humans communicate meaningfully with each other. Such theories can originate from a variety of different fields, including psychology, biology, and philosophy, though the actual study of the nature of communication is a field in and of itself. At its core, a communication theory is generally devoted to providing an explanation of how, exactly, one individual is able to communicate meaning to another and the degree to which the speaker and the listener can understand each other. Other theories are more focused on the historical and ritual significance of communication as an essential element of culture. Such theories may focus on the broad cultural effects of communication instead of the specific process of transmitting meaning.
The particular purpose of communication is often very important to a given communication theory, but different theorists often support different primary purposes of communication. A communication theory, for instance, may be based on the foundational understanding of communication as, first and foremost, the practical manner by which people can exchange ideas. Other theories, on the other hand, may examine communication itself as an idea divorced from the communicators, and will study the flow of information without specific regard for the exchange between two individuals. Additionally, some theories take a multifaceted approach to the purpose and basis of communication while others examine it from only one angle.
One important division between different theories is between the idea of communication as an exchange between social beings and communication as an exchange between biological organisms. Theorists on one side argue that man is a social being that is fundamentally different from other organisms, so an appropriate communication theory does not need to be rooted in biology. Theorists on the other side argue that because man is a biological organism, a communication theory can only be complete and useful if it can be firmly rooted in biology. Such theorists often examine the connections between human communication through language and non-linguistic animal communication.
The overall field of communication theory tends to focus on a few different possible views of language. The mechanistic view, for example, is based on the idea that one person communicates a message and the other person receives that message exactly as intended. Psychological models, on the other hand, take the psychological effects of communication into consideration and examine the manner in which the received message differs from the communicated one. A communication theory based in social ideas, however, examines the wider social implications of a message and may examine the manner in which ideas change as they travel from person to person. Such views may also examine language as a tool for manipulation and gathering power over others.