Piston (reciprocating) aircraft engines are internal combustion engines, similar to the type found in most automobiles. They are typically gasoline powered.
Piston aircraft engines are reciprocating internal combustion engines, similar to the type found most automobiles, which are used as powerplants in some aircraft, generally driving a propeller either directly or through a reduction-drive gearbox.
The first successful powered aircraft all used piston engines, which remained ubiquitous on aircraft of all sizes through the early-to-mid-1950s. However, the first workable jets were built and placed into military service during World War II, and the raw speed of jets and their ability to use practically any combustible liquid as fuel led them to quickly eclipse piston engines in fighter aircraft (with bombers following soon afterward). The first jet-airliner (the de-havilland-comet) entered commercial service in 1952, and the first widely-successful jetliner (the boeing-707) carried its first paying passengers in 1958; the large piston-engined airliners of the 1940s and 1950s, such as the lockheed-constellation, dc-7, and boeing-377-stratocruiser, fell almost entirely out of frontline passenger service by the end of the 1960s. Even for small, short-haul aircraft (where a jet's high speed provides little advantage, and its high fuel consumption provides a considerable disadvantage), piston engines were progressively replaced by turboprops, due to the latter's vastly-higher reliability (large piston engines, with their many cylinders, valves, pistons, sparkplugs, etc., are notoriously prone to suffering engine-failures) and their ability to run on the same fuels used for large jet aircraft. Since at least 1970, the main niche for piston engines in aviation has been small general-aviation aircraft, as small piston engines are much more reliable than their larger counterparts, and turbine engines scale down poorly to very small sizes.
Other powerplant types include: