Negative feedback inhibition occurs when "too much" of a substance results in decreased production of the same or a different substance. If having too much of a protein in a cell results in decreased transcription of the gene encoding the protein, then the protein was regulated by negative feedback. Another example (not listed here) would be the presence of too much sugar in the blood and repression of the glucagon gene to reduce production of sugar by other tissues.

While insulin and glucagon act in a negative feedback system, the question specifically asks for negative feedback inhibition. Turning on genes for insulin or glucagon would play a role in negative feedback, but would qualify as stimulation rather than inhibition.

Homeostasis is the tendency of a system to maintain internal equilibrium. As such, negative feedback is a very important component of homeostasis because negative feedback loops are often self-regulating, and are usually very stable. Negative feedback processes result in reduction to change from equilibrium by inhibiting processes that deviate from equilibrium.

When body temperature rises, negative feedback through thermoregulation helps to cool the body back to equilibrium temperature. This is achieved through peripheral vasodilation, increased breathing rate, and sweating.

In contrast, positive feedback is when a process reinforces and amplifies deviations from equilibrium. The luteinizing hormone (LH) surge during ovulation and uterine contractions during child birth are rare examples of positive feedback in biology.

Negative feedback reverses or shuts off a stimulus. When the body is experiencing dehydration, antidiuretic hormone is secreted, which works to decrease urine production, allowing the body to conserve fluids. When the body's fluids are replaced, negative feedback turns off antidiuretic hormone secretion. Catabolism is the breakdown of complex substances into simpler ones to release energy. Osmosis is the movement of water from an area of high concentration into an area of lower concentration. Vasoconstriction is a reduction in the diameter of a blood vessel. Antidiuretic hormone is also called vasopressin because it constricts blood vessels, which decreases urine output. Reabsorption is the taking back into the blood substances that had previously been filtered out from it. This occurs in the kidneys.

Negative feedback is the process of reestablishing a physiological set point. This is a corrective process. For example, during exercise, the body temperature increases. Negative feedback loops help bring the body temperature back down towards the set point of  by stimulating perspiration, dilating blood vessels to the extremities, etc. Positive feedback works in a way that exacerbates the effects of a stimulus. For example, during blood clotting, platelets bunch together in the area surrounding a wound. This causes more platelets to "get stuck" on the existing clump of platelets, causing further clotting.