A progressive cavity pump is a type of positive displacement pump and is also known as a progressing cavity pump, progg cavity pump, eccentric screw pump or cavity pump. It transfers fluid by means of the progress, through the pump, of a sequence of small, fixed shape, discrete cavities, as its rotor is turned.

A progressive cavity pump is used when the pumping application is not suited to acentrifugal pump. One of the clearest examples of when to use a progressive cavity pump is when the liquid has a higher viscosity, or thickness, than water.

The rotor seals tightly against the stator as it rotates, forming a set of fixed-sizecavities in between. The cavities move when the rotor is rotated but their shape or volume does not change. The pumped material is moved inside the cavities. The principle of this pumping technique is frequently misunderstood.