What is an internal combustion engine?

An internal combustion engine is defined as an engine that generates power through the combustion of fuel within its cylinders. This involves igniting a fuel-air mixture inside the engine's cylinders, leading to a series of mini-explosions that produce high-pressure gas. This gas then expands, pushing the pistons and creating mechanical energy to drive the engine's output.

The focus on combustion occurring within the cylinders is fundamental to what characterizes these types of engines. This process typically involves fuels like gasoline or diesel and is distinct from engines that utilize external combustion, where the combustion happens outside the engine (like in a steam engine). Internal combustion engines are commonly used in cars, motorcycles, and many other vehicles, making their definition significant when studying mechanical systems.

Understanding this fundamental characteristic helps differentiate internal combustion engines from other types, such as electric engines that rely purely on electrical energy for operation.