Humans are biologically classified as animals. Specifically, humans belong to the kingdom Animalia, which includes multicellular, eukaryotic organisms that are typically mobile and heterotrophic (obtain food by consuming other organisms). Humans are mammals within this kingdom and share many characteristics with other animals, such as possessing cells, having a nervous system, and undergoing processes like metabolism and reproduction. Although in everyday language "animal" is often used to refer only to non-human creatures, scientifically humans are part of the animal kingdom and the primate order. This means humans are a type of animal with unique traits such as advanced cognitive abilities and complex social behavior.