Peat is a dark brown or almost black material that sits under the ground in wet, spongy places called bogs. It is made of plants that died long ago but never fully broke down, because the water kept the air out. In parts of Ireland, Scotland, and northern Europe, people still cut it into blocks, dry it, and burn it to heat the house; it smells smoky and earthy. Gardeners mix peat into soil so pots hold water — though actually many now try to use less of it, because digging peat up wrecks the bog and lets stored carbon out into the air. Whisky makers in Scotland burn peat under the grain, and that is how some whiskies get their smoky taste. Peat is not ordinary garden dirt, and it is not coal yet; if it stayed buried and pressed for a very long time, it could slowly move toward coal.