Cybernetics is the interdisciplinary study of the structure of regulatory systems. As an oversimplification, Cybernetics is information theory, control theory and systems theory, at least in its first-order form. (Second-order cybernetics has crucial methodological and epistemological implications that are fundamental to the field as a whole.) Both in its origins and in its evolution in the second half of the 20th century, cybernetics is equally applicable to physical and social (that is, language-based) systems.

Cybernetics is only applicable when the system being analysed is involved in a closed signal loop; that is, where action by the system causes some change in its environment and that change is fed to the system via information (feedback) that enables the system to change its behavior. This "circular causal" relationship is necessary and sufficient for a cybernetic perspective.^{[citation needed]}System Dynamics, a related field, originated with applications of electrical engineering control theory to other kinds of simulation models (especially business systems) by Jay Forrester at MIT in the 1950s.