Nudity, or nakedness, is the state of wearing no clothing.
The deliberate and conscious wearing of clothing is a behavioural adaptation, which among all known extant and extinct animals is a uniquely human characteristic arising from functional needs such as protection from the elements. Protection from the elements includes the sun (for depigmented human populations) and cold temperatures after the loss of body hair and the migration of humans to colder regions (around 100,000 years ago) in which they had not evolved and thus lacked the necessary physical adaptations.
According to some researchers, wearing clothes may predate early human global migrations by an additional 70,000 years. In this case, the migrations were themselves facilitated by the innovation of clothing. It is believed that earlier species of archaic humans, including Homo neanderthalensis, Homo rhodesiensis, Homo heidelbergensis, and Homo antecessor, either were not able to create true clothing, or were not able to do it as well as Homo sapiens sapiens (anatomically modern humans). At most, as in the case of Homo neanderthalensis, they are believed to have worn only capes, if any coverings at all. This lack of behavioral adaptation, in turn, may have contributed to their eventual extinction during ancient climate changes when they may have succumbed to hypothermia, frostbite and other cold ailments.
The amount of clothing worn depends on functional considerations, such as a need for warmth, as well as social circumstances. In some situations, a minimum amount of clothing or none at all may be considered socially acceptable, while in others much more clothing may be expected. Social considerations involve cultural issues of modesty, subjective decency and social norms, besides other considerations, and these may depend on the context. There may also be legal considerations.