Whiskey (or whisky) is a type of distilled alcoholic beverage made from fermented grain mash. Various grains (which may be malted) are used for different varieties, including barley, corn, rye, and wheat. Whiskey is typically aged in wooden casks, which give it its characteristic flavor and color.

The process of making whiskey generally involves the following steps:

1. Malting: Barley or other grains are soaked in water and allowed to germinate, which activates enzymes that convert the starches in the grain into sugars.

2. Mashing: The malted grains are mixed with hot water to create a sugary liquid called "wort." Enzymes from the malted barley help to break down the starches into fermentable sugars.

3. Fermentation: Yeast is added to the wort, which converts the sugars into alcohol. This process typically takes a few days.

4. Distillation: The fermented liquid is heated in a still, which separates the alcohol from the water and other impurities. The initial distillation produces a low-proof spirit called "low wines."

5. Maturation: The low wines are typically matured in wooden casks, usually made from oak, for varying periods of time. During maturation, the whiskey develops its flavor and color, and takes on characteristics from the cask.

6. Bottling: After maturation, the whiskey is bottled and may be further diluted with water to reach the desired proof or alcohol content.

Different types of whiskey, such as Scotch, Irish, American, Canadian, and Japanese, have their own distinctive characteristics and regulations regarding ingredients, production methods, and aging.