Guinness is a stout that originated in the brewery of Arthur Guinness at St. James's Gate, Dublin, Ireland, in 1759. It is now owned by the British-based multinational alcoholic beverage maker Diageo. It is one of the most successful alcohol brands worldwide, brewed in almost 50 countries, and available in over 120. Sales in 2011 amounted to 850,000,000 litres. In spite of declining consumption since 2001, it is the best-selling alcoholic drink in Ireland where Guinness & Co. Brewery makes almost €2 billion worth of beer annually.

Stout is a dark beer that is generally warm fermented, such as dry stout, oatmeal stout, milk stout and imperial stout, though can also be cold fermented, such as Baltic porter.