The majority of a jet engine is made up of metal alloys, such as titanium, aluminum, and steel. These metals are chosen for their strength and resistance to high temperatures and stresses. The blades of the compressor and turbine are often made of a combination of metals, such as titanium and nickel, to provide added durability. The combustor, which is where the fuel is burned, is typically made of a ceramic material to withstand the high temperatures. Other components, such as bearings and seals, are made of specialized materials that can withstand the extreme conditions found in a jet engine.