The document discusses internal combustion engines. It defines an ICE as an engine where combustion of an air-fuel mixture occurs within a combustion chamber, applying force to move components. ICEs are classified based on their cycle of operation (Otto or diesel), fuel used (gasoline, diesel, gas), charging/cooling methods, cylinder arrangement, camshaft layout, and more. ICEs are used in various applications like road vehicles, aircraft, marine vehicles, and power generation.