An igloo, also known as a snow house or snow hut, is a type of shelter traditionally built from blocks of compacted snow, particularly by the Inuit people of the Arctic. 

The snow’s insulating properties help retain heat, making the interior of an igloo surprisingly warm, even in extremely cold environments. They are usually dome-shaped and can vary in size, from small, temporary shelters for hunters to larger, more permanent dwellings. The snow blocks are carefully arranged in a spiral pattern to form the structure, with a small tunnel entrance to help minimize heat loss.