Moonshine is high-proof liquor, traditionally made or distributed illegally. The name was derived from a tradition of distilling the alcohol at night to avoid detection. In the first decades of the 21st century, commercial distilleries have adopted the term for its outlaw cachet and have begun producing their own legal "moonshine", including many novelty flavored varieties, that are said to continue the tradition by using a similar method or locale of production.

In 2013, moonshine accounted for about one-third of global alcohol consumption.

Different languages and countries have their own terms for moonshine .

The ethanol may be concentrated in fermented beverages by means of freezing. For example, the name applejack derives from the traditional method of producing the drink, jacking, the process of freezing fermented cider and then removing the ice, increasing the alcohol content. Starting with the fermented juice, with an alcohol content of less than ten percent, the concentrated result can contain 25–40% alcohol by volume (ABV).

In some countries, moonshine stills are illegal to sell, import, and own without permission. However, enthusiasts explain on internet forums how to obtain equipment and assemble it into a still. To cut costs, stainless steel vessels are often replaced with plastic stills, vessels made from polypropylene that can withstand relatively high heat.

The preferred heat source for plastic stills or spiral stills is sous vide sticks; these control temperature, time, and circulation, and are therefore preferred over immersion heaters. Multiple units can be used to increase the wattage. Also, sous vide sticks, commonly sold in 1200 W and generally temperature regulated up to 90 °C (194 °F) (ethanol boils at 78 °C (172 °F)), will evaporate the ethanol faster than an immersion heater, commonly sold in 300 W. Electrical injury may occur if immersion heaters are modified, such as if a 35 °C (95 °F) thermostat is removed from an aquarium heater (because doing so may break its waterproofing), or if an immersion heater is disassembled from an electric water boiler.

A plastic still is a device for distillation specially adapted for separating ethanol and water.^{[citation needed]} Plastic stills are common because they are cheap and easy to manufacture. The principle is that a smaller amount of liquid is placed in an open smaller vessel inside a larger one that is closed. A cheap 100 W immersion heater is typically used as heat source, but a thermal immersion circulator, like a sous vide stick is ideal because it comes with a temperature controller. The liquid is kept heated at about 50 °C (122 °F) which slowly evaporates the ethanol to 40% ABV that condense on the inner walls of the outer vessel. The condensation that accumulates in the bottom of the vessel can then be diverted directly down through a filter containing activated carbon. The final product has approximately twice as much alcohol content as the starting liquid and can be distilled several times if stronger distillate is desired. The method is slow, and is not suitable for large-scale production.

Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fractionate. Generally the component parts have boiling points that differ by less than 25 °C (45 °F) from each other under a pressure of one atmosphere.