A dwelling is a self-contained unit of accommodation used by one or more households as a home. It can be a house, apartment, mobile home, houseboat, recreational vehicle, or other "substantial" structure. Legal definitions vary by jurisdiction, but generally, a dwelling is defined as a building, structure, or portion thereof which is occupied as, or designed or intended for occupancy as, a residence by one or more families. A dwelling can be a shelter, such as a house, in which people live. It can be a permanent building or structurally separated part thereof, such as a detached house or unit of an apartment building. Tents, trailers, and igloos are also considered dwellings.