In daily life sometimes we need to separate a substance from its mixture. In this chapter we will discuss why do we separate substances, and what to do with the products after separation. We also study the method of separation like handpicking; threshing; winnowing; sieving, sedimentation, decantation, and filtration; evaporation. Also in some cases, we will discuss why and how to apply more than one method. At last we study about can water dissolve any amount of a substance.