What is cybernetics?
In short, the science of communications and automatic control systems in both machines and living things.
For a more thorough explanation, Wikipedia actually provides an excellent definition:
Cybernetics is a transdisciplinary approach for exploring regulatory systems—their structures, constraints, and possibilities. Norbert Wiener defined cybernetics in 1948 as “the scientific study of control and communication in the animal and the machine.” In the 21st century, the term is often used in a rather loose way to imply “control of any system using technology.” In other words, it is the scientific study of how humans, animals and machines control and communicate with each other.
(…) The essential goal of the broad field of cybernetics is to understand and define the functions and processes of systems that have goals and that participate in circular, causal chains that move from action to sensing to comparison with desired goal, and again to action. Its focus is how anything (digital, mechanical or biological) processes information, reacts to information, and changes or can be changed to better accomplish the first two tasks. Cybernetics includes the study of feedback, black boxes and derived concepts such as communication and control in living organisms, machines and organizations including self-organization.
(retrieved March 1, 2018)
Wiener N (1948). Cybernetics. Cambridge Technology Press.