Guinness ( ) is a popular dry stout alcoholic drink that originated in Arthur Guinness' brewery at St. James's Gate in Dublin. Guinness is based on the porter style that originated in London in the early 18th century and is one of the most successful beer brands worldwide. A distinctive feature is the burnt flavor which is derived from the use of roasted barley. For many years a portion of the drink was aged to give a sharp lactic flavour, although Guinness has refused to confirm if this still occurs, possibly for secrecy. The thick creamy head is the result of the beer being mixed with nitrogen when being poured. It is popular with Irish people both in Ireland and abroad and, in spite of a decline in consumption over recent years, is the best-selling alcoholic drink of all time in Ireland where Guinness & Co. makes almost €2 billion annually.

The parent company has been headquartered in London since 1932 and was later merged with Grand Metropolitan plc and developed into a multi-national alcohol conglomerate named Diageo.

History

Arthur Guinness started brewing ales initially in Leixlip, then at the St. James's Gate Brewery, Dublin, Ireland from 1759. On December 31, he signed (up to) a 9,000 year lease at £45 per annum for the unused brewery. Ten years later on 19 May 1769 Guinness exported his ale for the first time, when six and a half barrels were shipped to England.

Although sometimes believed to have originated the stout style of beer, the first use of the word stout in relation to beer was in a letter in the Egerton Manuscript dated 1677, almost 50 years before Arthur Guinness was born. Arthur Guinness started selling the dark beer porter in 1778. The first Guinness beers to use the term were Single Stout and Double Stout in the 1840s.

The breweries pioneered several quality control efforts. The brewery hired the statistician William Sealy Gosset in 1899, who achieved lasting fame under the pseudonym "Student" for techniques developed for Guinness, particularly Student's t-distribution and the even more commonly known Student's t-test.

Guinness brewed their last porter in 1974.

Guinness acquired the Distillers Company in 1986.

The Company merged with Grand Metropolitan in 1997 to form Diageo plc.

The Guinness brewery in Park Royal, London closed in 2005. The production of all Guinness sold in the UK and Ireland was switched to St. James's Gate Brewery Dublin.

Guinness has also been referred to as "Black 1" and as a "Pint of Plain" - referred to in the famous refrain of Flann O'Brien's poem "The Workman's Friend": "A pint of plain is your only man."