Sugar is separated from its impurities by the process of crystallization. Crystallization involves dissolving a solid, in this case, sugar, in a solvent, usually water, to create a saturated solution. The solution is then cooled or allowed to evaporate, causing the sugar to come out of the solution and form crystals. The impurities remain dissolved in the solution or get trapped in the crystal lattice of the sugar, making it possible to separate the pure sugar crystals from the impurities. Precipitation, distillation, and evaporation are other methods of separating substances but are not typically used for separating sugar from its impurities.