Friction involves rubbing one body surface against another while maintaining constant and equal pressure in all directions. The term friction (frik-shon) comes from the French term frictionner, meaning "to rub". Movements may be linear or circular. Unlike effleurage, in which pressure is unequal when applied in two or more directions (centripetal = deeper pressure), frcition involves equal pressure in all directions. These movements can produc heat and may stimulate therapeut