Liquid rocket propellants often require the largest component volume aboard a rocket vehicle. They must be contained by very bulky and heavy tanks that keep the liquids at the right pressure and temperature until they are used in a rocket engine. An increase in the propellant density, or mass per volume, can reduce the mass of the tanks, structure, and other parts of the rocket that depend upon the propellant volume. The use of higher-density propellants is therefore an excellent way to improve the performance of rocket vehicles. Reducing the mass of the rocket will lead in turn to a reduction in the weight of fuel needed to move the rocket, so there is a powerful cascade effect.