In a distillery, a unit operation, crude oil is distilled into fractions for specific uses, water is distilled to remove impurities and air is distilled to separate out its components to get oxygen, or argon or nitrogen. Earlier forms of distillation worked to form batches using vaporization and its opposite component method of condensation, but multiple batches were required to get a pure
. compound. In simple distillation hot vapors produced are immediately channeled into a condenser which cools down and the condenses the formerly hot vapors at given temperatures and pressures, so this simple method is used to separate liquids that have greatly different boiling points or to separate liquids from involatile oils or solids of any kind. Fractional distillation, on the other hand, separates components well within a fractionating column and this distillation through successive distillations is the rectification method of distillation; for more on this see http://en.wikipedia.org/wiki/Distillation.
