The core components of a turbofan engine are the combustion chamber, the high-pressure turbine, and the high-pressure compressor. Combined, they provide the driving force for the engine.
The combustion is the most fundamental source of power; the high-pressure turbine spins the entire engine by harnessing the force from the combustion chamber.
The high-pressure compressor has the most functions, operating under the power of the high-pressure turbine. It provides a high-pressure air source for the combustion chamber, as well as high-pressure air for pressurizing the aircraft cabin, cooling high-temperature components such as the turbine blades, and de-icing and anti-icing the air intake, among other uses.
Furthermore, a certain amount of power is transmitted from the high-pressure compressor rotor shaft through gears to operate various engine accessories, such as the lubricating oil pump, fuel pump, starter, as well as the aircraft's generator and hydraulic pump, and so on.