An igloo is a dome-shaped structure built by the Inuit people of Eastern Siberia, Greenland, Alaska and parts of Canada out of snow. Igloos are constructed with dry, hard snow, which provides insulation from wind and cold. An igloo's interior can be up to 40 degrees warmer than the outside.
The shape of an igloo is called a catenoid, and provides structural stability. A properly constructed igloo can support the weight of a person standing on its roof. The igloo's strength and insulation ability increases over time as the snow repeatedly melts and refreezes.
The smallest are temporary structures that accommodate a single hunter, often on open sea ice. Intermediate-size igloos accommodate an entire family. Larger igloos could have up to five rooms and are used for ceremonial purposes.
Although many people associate the word "igloo" with the snow structures, the Inuit word simply means "dwelling," and an igloo can be built of driftwood or animal skins.