Field-flow fractionation, abbreviated FFF, is a separation technique where a field is applied to a fluid suspension or solution pumped through a long and narrow channel, perpendicular to the direction of flow, to cause separation of the particles present in the fluid, depending on their differing "mobilities" under the force exerted by the field. It was invented and first reported by J. Calvin Giddings. The method of FFF is unique to other separation techniques due to the fact that it can separate materials over a wide colloidal size range while maintaining high resolution. Although FFF is an extremely versatile technique, there is no "one size fits all" method for all applications.