Shelter is any thing that protects a person from his/her environment, including dangerous cold and heat and allow restful sleep, another human need.

A shelter can range from a natural shelter; such as a cave or a fallen-down (cracked but not split) thickly-foliaged tree, to an intermediate form of man-made shelter such as a debris shelter, a ditch dug next to a tree log and covered with foliage, or a snow cave, to completely man-made structures such as a tarp, tent, or house.