Crystallization: Mainly used for purifying substances by forming crystals from a precipitating solution. Crystallization refers to the forming of solid crystals from a homogenous (solution) mixture.
An example would be forming pure salt crystals. This is done by dissolving the impure salt into a solvent such as water. The salt solution is then allowed to cool. As it does, pure salt crystals would form at the bottom of the water, whereas, the impure substances would be left in the water. The crystals can then be rinsed with a chilled solution and dried.