A type of system that reduces the difference between a current state and a goal state, whilst there remains a deficit. An example of this is a thermostat (regulation of external temperature), or a refrigerator (regulation of internal temperature), which works to maintain a variable (the temperature). The less obvious Negative feedback loops are found in Businesses maintaining product-market fit. The activity of adjusting to fit is called ‘Adaptation’. (See also ‘Adaptation’).