A ranch style home in Salinas, California A house is a building typically lived in by one or more people. The word "house" may also refer to a building that shelters animals, especially in a zoo.[1] It generally has walls and a roof to shelter its enclosed space from precipitation, wind, heat, cold, and other elements. The social unit that lives in a house is known as a household. Most commonly,[citation needed] a household is a family unit of some kind, though households can be other social groups, such as single persons, or groups of unrelated individuals. Settled agrarian and industrial societies are composed of household units living permanently in housing of various types, according to a variety of forms of Land tenure. English-speaking people generally call any building they routinely occupy "home". Many people leave their house during the day for work and recreation but typically return to it to sleep or for other activities. See: List of house types.