Guinness Irish Stout is a strong black porter brewed in Dublin since the eighteenth century, by Arthur Guinness & Co., now owned by the global conglomerate Diageo. The drink is noted for its distinctive deep black body and creamy white head, although it shares these characteristics with other Irish stouts such as Beamish and Murphy's.
Guinness is enjoyed throughout the world, but especially in Ireland, the UK, Africa and the Caribbean. It is also brewed in many countries throughout the world, although it is popularly held that the best Guinness is that which is served within a short radius of the original brewery in St. James's Gate, Dublin. This brewery is thoughtfully equipped with a visitors centre, the Guinness Storehouse, where you can test out this theory.
A "proper" pint of Guiness should be poured in "Guinness Time": roughly three quarters of the pint is pulled, and then left to settle. Once the head has fully formed, the glass is then topped up. This convention is often disregarded outside Ireland, which is one reason why people think Guinness tastes better in Ireland. Another reason is that the lines which carry the Guinness from keg to tap are treated with a special reverence in Ireland, and are generally always kept scrupulously clean.