Single malt Scotch is single malt whisky made in Scotland. To be a single malt scotch the whisky must have been distilled at a single distillery using a pot still distillation process and made from a mash of malted grain. In Scotland, the only grain allowed to be used in a single malt whisky is barley. As with any Scotch whisky, a single malt Scotch must be distilled in Scotland and matured in oak casks in Scotland for at least three years, and one day. (Most single malts are matured longer.)
Until the Scotch Whisky Regulations 2009 (SWR 2009), the word "blended" only appeared (in the context of Scotch whisky) on bottles of whisky that contained a mixture of both barley and non-barley grain whisky, but this is no longer the case. Under the terminology established by the SWR 2009, a "blended malt Scotch whisky" is a mixture of single malt Scotch whiskies, not a mixture of malted barley whisky and non-barley whisky; those are called "blended Scotch whisky", without the word "malt". The term "blended malt" replaced "vatted malt" used under the prior labelling conventions.
The age statement on a bottle of single malt Scotch is the number of years the whisky spent maturing in casks. Very few whiskies are bottled from a single cask, and the mixing of spirits with different amounts of ageing is allowed; the age statement reflects the age of the youngest whisky in the mix.
Distillation of whisky has been performed in Scotland for centuries. The earliest written record of whisky production in Scotland from malted barley is an entry on the 1494 Exchequer Rolls, which reads "Eight bolls of malt to Friar John Cor, by order of the King, wherewith to make aqua vitae."
In the following centuries, the various governments of Scotland began taxing the production of whisky, to the point that most of the spirit was produced illegally. However, in 1823, Parliament passed an act making commercial distillation much more profitable, while imposing punishments on landowners when unlicensed distilleries were found on their properties. George Smith was the first person to take out a licence for a distillery under the new law, founding the Glenlivet Distillery in 1824.