Overview
In feedback loops a chain of cause and effect exists where a state variable of a system has a feedback loop influencing its own rate of change. Such feedback can be direct, or can be via other state variables.
Such systems can give rich qualitative behaviors, but whether the feedback is positive or negative in sign is an extremely important influence on the results.
In positive feedback, the derivative of the variable is positively affected by the variables value, and the opposite is true in negative feedback.
A key feature of positive feedback is thus that small disturbances get bigger. When a change occurs in a system, positive feedback causes further change, in the same direction.
Read more about this topic: Positive Feedback