In mammals, conditions such as water concentration, temperature and glucose concentration must be kept as constant as possible. These are examples of homeostasis.
A negative feedback mechanism is an important type of control that is used in homeostasis. A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback.
An example of negative feedback is the control of body temperature.
If the body gets too hot, it begins to sweat to try to reduce the temperature. If the body gets too cold, it begins to shiver to try to raise the temperature.
The glucose concentration in the blood is also controlled by negative feedback mechanisms.