Guinness is a popular Irish dry stout that originated in the brewery of Arthur Guinness (-) at St. James's Gate, Dublin. Guinness is one of the most successful beer brands worldwide. It is brewed in almost 60 countries and is available in over 100. 850 million litres (1.5 billion imperial or 1.8 billion US pints) are sold annually. A feature of the product is the burnt flavour that is derived from roasted unmalted barley, although this is a relatively modern development, not becoming part of the grist until the mid-20th century. For many years a portion of aged brew was blended with freshly brewed beer to give a sharp lactic flavour. Although the Guinness palate still features a characteristic 'tang', the company has refused to confirm whether this type of blending still occurs. The draught beer's thick, creamy head comes from mixing the beer with nitrogen when poured.