kotatsu

thumb|A modern Japanese kotatsu thumb|The underside of an electric kotatsu, with the heater visible in the centre thumb|Edo period|Edo-period kotatsu at the Fukagawa Edo Museum

A is a low, wooden table frame covered by a futon, or heavy blanket, upon which a table top sits. Underneath is a heat source, formerly a charcoal brazier but now electric, often built into the table itself. Kotatsu are used almost exclusively in Japan, although similar devices for the same purpose of heating are used elsewhere, e.g. the Spanish brasero or Iranian korsi.