Feedback loops react to change to adjust flows.

Feedback loops monitor a stock and trigger an adjustment to the in- or outflows when certain changes to the stock are identified. Feedback loops are generally classified as balancing feedback loops, which try to keep a stock within specific parameters, and reinforcing feedback loops, which accelerate upward as stock increases, or downward as it decreases. Feedback loops are necessarily adjacent to delays, as each aspect relating to a feedback loop is a time-based reaction.