A damper is a plate that is located in a fireplace, and it moves to allow smoke, carbon monoxide and fumes to travel up the chimney and out of your home. Dampers were commonly used in old stoves that relied on wood as a fuel source. An example is one of the old-style wood burning fireplaces that have two small dampers on the front door. The dampers open with a few twists. When the plates are opened further, they allow more air to blow into the chimney, and this creates a constant flow of fresh cool air that carries oxygen into your fire. The flow also conducts air up through the chimney and out of your home. Dampers can also be located inside a fireplace, but the key characteristics are the same. Dampers are usually made of steel and must open and close to facilitate air circulation through a fireplace.