Distilling is actually a method of purification. In the petrochemical industry it is often used to separate crude oil into light rocket fuel and heavy diesel. This separation is based on the difference of the boiling temperature of the various molecules present in the crude oil. The same principle can be applied to a liquid mixture containing alcohol: after heating (and not boiling) a new liquid spirit is obtained with a higher alcohol percentage than first liquid. Beer is used in the production of whisky, gin and Dutch genevers. Cider (wine of apples) is used to produce calvados. Wine (of grapes) is used in the production of brandy or armagnac. The leftovers of wine production are used for grappa, marc or pisco. Do you have any questions concerning distilling? Do you want to know more theoretical background? Let me know via the contact page!