A chimney's a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what's known as the stack, or chimney, effect. The space inside a chimney's called a flue. Chimneys may be found in buildings, steam locomotives and ships. In the US, the term smokestack (colloquially, stack)'s also used when… (More on Chimney)