The internal combustion engine is one of the most widely used mechanical devices in our world today. According to Wikipedia, an “internal combustion engine is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit.” Through a series of expansion and combustion, the chemical energy is then converted to mechanical energy. It can be used to power your car, your recreational vehicles, lawn mowers, and much more. There are many different types as well; the most common are two stroke, four stroke, rotary, and diesel engines. The internal combustion engine has been around for many centuries. According to About.com the earliest recording of an internal combustion engine design was 1680. This was designed, but never built, by Christian Huygens and was fueled by gunpowder. From then on, many other engineers have spent time designing and building engines, to which some failed and others prevailed.
http://bancroft.berkeley.edu/Exhibits/physics/origins02.html