A turbocharger is a device driven by exhaust gas which pressurises the air going into the engine, increasing the engine's power output.

Turbochargers combine a turbine wheel and a compressor wheel, connected together on a single shaft. The turbine is placed in the exhaust system and driven by exhaust gas, so the turbocharger uses energy from the exhaust gas to drive it. The compressor is placed in the engine's intake system, and as it spins it increases the pressure in the intake, forcing more air into the cylinders. This allows more fuel to be burned, which means more power can be produced.

Compare supercharger.