Homeostasis is the tendency of living things to mantain a healthy or desired state. This applies to internal state such as body temperarure -- humans shiver to generate heat through muscle movement when too cold; and dogs pant to lose heat through evaporation when too hot. It also applies to external state such as the small balancing movements we make when standing. Similarly robots and forms of artificial life need to maintain 'healthy' state, such as not overheating or running out of energy.
Used on Chap. 15: page 360