constitute the second most diverse family of artiodactyla after bovids. Though of a similar build, are strongly distinguished from antelopes by their antlers, which are temporary and regularly regrown unlike the permanent horns of bovids. Characteristics typical of deer include long, powerful legs, a diminutive tail and long ears.[The elk stands 1.4–2 metres (4.6–6.6 ft) at the shoulder and weighs 240–450 kilograms (530–990 lb). The northern pudu is the smallest in the world; it reaches merely 32–35 centimetres (13–14 in) at the shoulder and weighs 3.3–6 kilograms (7.3–13.2 lb). The southern pudu is only slightly taller and heavier. Sexual dimorphism is quite pronounced – in most species males tend to be larger than females, and, except for the reindeer, only males possess antlers.
Coat colour generally varies between red and brown, though it can be as dark as chocolate brown in the tufted deer or have a grayish tinge as in elk. Different species of brocket vary from gray to reddish brown in coat colour. Several species such as the chital, the fallow and the sika  feature white spots on a brown coat. Coat of reindeer shows notable geographical variation. undergo two moults in a year; for instance, in red deer the red, thin-haired summer coat is gradually replaced by the dense, greyish brown winter coat in autumn, which in turn gives way to the summer coat in the following spring. Moulting is affected by the photoperiod.
They are also excellent jumpers and swimmers. They are ruminants, or cud-chewers, and have a four-chambered stomach. Some such as those on the island of Rùm, do consume meat when it is available.
Nearly all have a facial gland in front of each eye. The gland contains a strongly scented pheromone, used to mark its home range. Bucks of a wide range of species open these glands wide when angry or excited. All deer have a liver without a gallbladder.