An igloo (Inuit language: iglu, Inuktitut syllabics: ᐃᒡᓗ, "house", plural: iglooit or igluit, but in English commonly igloos), translated sometimes as snowhouse, is a shelter constructed from blocks of snow, generally in the form of a dome. Although igloos are usually associated with all Inuit, they were predominantly constructed by people of Canada's Central Arctic and Greenlands Thule area. Other Inuit people tended to use snow to insulate their houses which consisted of whalebone and hides. The use of snow is due to the fact that snow is an insulator (due to its low density). On the outside, temperatures may be as low as −45 °C (−49 °F), but on the inside the temperature may range from −7 °C (19 °F) to 16 °C (61 °F) when warmed by body heat alone .

There are three types of igloo, all of different sizes and all are used for different purposes.

The smallest is constructed as a temporary shelter, usually only used for a one or two nights. These were built and used while during hunting trips, often on open sea ice.

Next in size was the semi-permanent, intermediate sized family dwelling. This usually was a single room dwelling that housed one or two families. Often there were several of these in a small area, which formed an "Inuit village".

The largest of the igloos was normally built in groups of two. One of the buildings was a temporary building constructed for special occasions, the other was built nearby for living. These could have up to five rooms and housed up to 20 people. A large igloo may have been constructed from several smaller igloos attached by their tunnels giving a common access to the outside. These were used to hold community feasts, and traditional dances.