Beach drift refers to the characteristic zigzag (saw-tooth) net movement of sediment particles along a beach face, caused by the asymmetry between the swash (which runs obliquely up the beach in the direction of oblique wave approach) and the backwash (which flows straight back down the beach under gravity), resulting in a net lateral transport of sediment along the shoreline on the beach itself, distinct from longshore drift/current which refers to net sediment transport within the surf/nearshore zone by longshore currents.