1. Purification: Crystallization is a powerful technique for purifying substances. When a solution containing impurities is cooled or the solvent is evaporated, the pure compound will crystallize out, leaving the impurities behind in the solution. This is widely used in the pharmaceutical industry to produce high-purity drugs, and in chemical laboratories to isolate and purify products.

2. Growth of Single Crystals: Single crystals, which are large, continuous pieces of a crystalline material with a regular, repeating arrangement of atoms, are important for a variety of technologies. Crystallization is the process used to grow these crystals. Examples include:

* Semiconductor Industry: Silicon crystals are the foundation of microchips and computer processors.

* Laser Technology: Many lasers rely on single crystals of specific materials like ruby or titanium sapphire.

* Optical Devices: Crystals with specific optical properties, like quartz or potassium dihydrogen phosphate (KDP), are used in lenses, prisms, and other optical devices.