This technique most widely used in this technique small quantity of the sample solution is introduced at the top of column. Pure solvent is then poured down the column this gives rise to differential migration of solutes In mobile phase.Each solute emerges from the Column exit depending on its partition coefficient.If the partition coefficient for the solutes in the sample are sufficiently different the mixture separates out into bands which migrate at different rates for s.p than sample components represents small fraction of column capacity