Single Malt refers to a type of whiskey that is made from only one type of malted grain (almost always barley) and is produced at a single distillery. This term is most commonly associated with Scotch whisky, although it can apply to malt whiskeys from other countries as well.

Key characteristics of single malt whiskey include:

1. **Single Grain Source**: It is made exclusively from malted barley. No other grains are used in the production.

2. **Single Distillery**: The entire production process, including fermentation, distillation, and aging, takes place at one distillery. This is in contrast to blended whiskeys, which can be made by combining malt whiskeys from different distilleries, and often include grain whiskeys as well.

3. **Distillation**: In Scotland, single malt whiskey is typically distilled twice (and sometimes three times) in pot stills, which is a traditional method of distillation.

4. **Aging**: It must be aged in oak barrels. In Scotland, the minimum aging period is three years, but many single malts are aged much longer.

5. **Geographical Indication**: In the case of Scotch whisky, the term "single malt" implies that the whiskey is produced in Scotland. However, other countries, including Japan, the United States, and Ireland, also produce single malt whiskeys.

Single malt whiskeys are appreciated for their complexity and variety of flavors, which can be influenced by the specific characteristics of the malt, the distillation process, the type of cask used for aging, and the length of time the whiskey is aged. They are often regarded as premium products in the world of whiskey.