A set of objects together with relationships between the objects and between their attributes. A natural social system which responds automatically to forces which threaten its survival or well-being or those of its members. Systems can be open or closed. Open systems with permeable boundaries are more apt to stay dynamic and flourish, or at least continue to function. In general systems theory a change in one part of the system affects all other parts, due to relationships and interdependence of the parts.
Input generates energy for the open system.
Oil is put in. Heat is put out. If we have a thermostat hooked up to the furnace to measure the air temperature in a room, it will tell the furnace when to stop putting out heat and when to re-start oil going in to produce more warmth. Hence output becomes part of feedback. The elements in a system are in constant and meaningful interaction.