The most basic laboratory centrifuge is a test-tube centrifuge. Test tubes are placed in a holder, the lid is closed and the tubes are spun. The resulting centrifugal force causes the denser components to move to the bottom of the tube, with the less dense components above them.

Centrifugation is the process of concentrating the natural forces that act on all particles of different densities to accelerate the natural process of separation. It is what separates the particles by density in the test tube. Centrifugation can occur with either filtration or sedimentation methods.