Distillation works by heating a mixture until a substance boils off, which can then be collected in another container after condensing. Distillation is only effective if the substances in the original mixture have significantly different boiling points, so that all of one substance can be boiled off before the other(s) start to turn to gas as well.
Distillation is used in several commercial applications, including heavily in the oil-processing industry. Additionally, distillation is involved in key steps in creating different types of alcohol, like vodka. It can also be used to purify contaminated water. Evidence of distillation systems date back to ancient Greece in the second century.