Hallux

The hallux, also called the big toe, is the toe innermost (closest to the middle of the body) of the foot. It is usually the biggest toe in the body. 
In humans, the hallux is longer than the toes next to it; this is inherited. Humans are unusual amongst hominids in walking upright, and their feet are adapted to their locomotion.
In other animals the foot is organised differently. Mammals usually move on four legs with paws. In some birds, the hallux is pointed backwards: it helps to grip.