In the mammalian respiratory system, eupnea is normal, good, healthy and unlabored breathing, sometimes known as quiet breathing or a resting respiratory rate In eupnea, expiration employs only the elastic recoil of the lungs. Eupnea is the unaffected natural breathing in all mammals, including humans.

Hyperpnea is breathing more deeply and sometimes faster than usual. It's normal during exercise or exertion. Tachypnea is rapid, shallow breathing, when you take more than the normal amount of breaths per minute.