Bipedalism

Bipedalism is defined by the Merriam-Webster Dictionary as the condition of having or using only two feet for locomotion, and is found in a few groups of animals on Earth. Humans and birds are examples of organisms that use bipedal movement as their primary means of terrestrial locomotion, but many animals are capable of bipedal movement under the correct circumstances (i.e. some lizards run on their hind limbs to enable faster movement, and some primates walk bipedally to wade through marshes or other water features).

The use of bipedal movement is thought to be a key element in human evolutionary history, as it is part of what separates humans and their ancestors from the other Great Apes.