Deer species are a group of mammals that belong to the family Cervidae. They are characterized by their long legs, antlers, and herbivorous diet. There are over 90 different species of deer found throughout the world, with the most common being the white-tailed deer, mule deer, and red deer. Deer species are important both ecologically and economically, as they play a vital role in many ecosystems and are hunted for their meat and antlers.