A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.
The power for the supercharger can be provided mechanically by employing a belt, gear, shaft, or chain connected to the engine’s crankshaft. When power is supplied by a turbine powered by exhaust gas, a supercharger is known as a turbosupercharger – typically referred to simply as a turbocharger or just turbo.
Common usage restricts the term supercharger to mechanically driven units.