Liquor is produced by distilling a fermented solution derived from fruit or grain. However, producing liquor at home is illegal in many locations, even if for personal use. It is necessary to consult your local and state laws before becoming a home-distiller.
Distillation is a process that began as early as 2000 BCE. The process is used to produce all types of liquor and spirits, from vodka to brandy. The process starts by evaporating the alcohol out of the base solution. The alcoholic vapor then passes through a cooling tube, which condenses the vapor back into an alcoholic liquid, thus producing liquor. Variation between different types of liquor is based on the type of base solution used for evaporation. For example, vodka is produced by evaporating, or distilling, the alcohol out of a very bland potato-based solution, while Scotch is often produced from the alcohol of a peat-smoked grain solution.
Further variation between different types of liquor results from processes that occur after distillation. Aging is a process wherein the distilled spirit is left to sit in a vessel, which imparts additional depth and flavor upon the spirit. These vessels can range from small charred oak barrels to massive stainless steel vats. A distiller's choice of vessel, as well as the length of time the alcohol spends in contact with the vessel, depends on the type and depth of flavor he wants to create in the final product.