As of 2015, websites such as RockfordChimneySupply.com and HighsChimney.com provide fireplace damper diagrams. The sites also provide detailed information about fireplace dampers. Various fireplace designs have different types of dampers.
Both of these sites offers different types of diagrams. For example, RockfordChimneySupply.com shows an interactive fireplace diagram with two dampers: top damper and throat damper. HighsChimney.com has a colored diagram indicating the components of a fireplace including the damper.
A fireplace damper is a device whose primary purpose is to slow down heated air from going up a chimney. A damper also prevents animals from entering a home through the chimney.