Crepuscular animals are those that are active primarily during twilight (i.e., the period before dawn and that after dusk). It is thus to be distinguished from diurnal and nocturnal behavior where an animal is active during the hours of daylight or the hours of darkness respectively. The term is not precise however as some crepuscular animals may also be active on a moonlit night or during an overcast day. The term matutinal is used for animals that are only active before dawn, and vespertine for those only active after sunset.