Most road vehicles utilise an internal combustion engine which produces a series of small explosions within a confined chamber which, in turn, forces the physical movement of components to create drive. For combustion to occur, oxygen is required which is drawn into the system and then exported through your exhaust. If the movement of air is quickened, the engine is then able to produce more power: this is the basic concept of a turbo.
The turbo itself is made of two turbine connected by one shaft. One turbine works with gases exiting from the engine through the exhaust while the other is involved with the air entering through the intake system. The gases exiting the engine spin one turbine at speeds of up to 250,000 rpm and temperatures of up to 900 degrees. These gases continue through and out of the vehicle through the exhaust.
The turbines are connected by a shaft and so the movement of the exhaust turbine caused the other to move. The other turbine is connected to the air intake system and increases the speed at which air is fed to the engine. This increase in the flow of air improves engine efficiency and power.