Stout and porter are dark beers made using roasted malts or roast barley. There are a number of variations including Baltic porter, dry stout, and Imperial stout. The name Porter was first used in 1721 to describe a dark beer popular with street and river porters of London that had been made with roasted malts. This same beer later also became known as stout, though the word stout had been used as early as 1677. The history and development of stout and porter are intertwined.
Porter was first recorded as being made and sold in London in the 1730s. It became very popular in Great Britain and Ireland, and was responsible for the trend toward large regional breweries with tied pubs. With the advent of pale ale the popularity of dark beers decreased, apart from Ireland where the breweries of Guinness, Murphy's and Beamish grew in size with international interest in Irish (or dry) stout. (Full article...)