A dugout or dug-out, also known as a pit-house, earth lodge, mud hut, is a shelter for humans or domesticated animals and livestock based on a hole or depression dug into the ground. Dugouts can be fully recessed into the earth, with a flat roof covered by ground, or dug into a hillside. They can also be semi-recessed, with a constructed wood or sod roof standing out. These structures are one of the most ancient types of human housing known to archeologists, and the same methods have evolved into modern "earth shelter" technology.