Fans at the front of the jet or gas turbine draw air into the engine. In fact for most large commercial airliners, a specific type of jet a "turbo-fan" as pictured is used. In this case only some of the the air is pulled through the engine cycle, the oversized fan at the front blows the rest straight out to deliver more thrust when required, but better economy in flight.

Air that is drawn into the engine is compressed through a series of rotating and fixed blades. Known as "rotors" and "stators" these blades can compress the air by 40 times, and this process generates an immense amount of heat.

The compressed and hot air is mixed with fuel and ignited in the combustion chamber. The mixture is carefully controlled to ensure that there is a constant flame. The burnt gases expand rapidly and move to exit the engine.

Before the expanding gases can exit the engine they flow through the turbine. The turbine consists of further blades and these gases spin them and the central engine shaft as they exit through to the exhaust. The shaft spins the fan blades at the front of the engine drawing in more air air and ensuring the process continues.