March 17th is St Patrick’s Day – a celebration of all things Irish – and people around Ireland and throughout the world will commemorate it with a pint or two of Guinness, Ireland’s unofficial national intoxicant with more than a 25% share of the beer market.

Arthur Guinness founded the brewery that makes the famous drink. Born in 1725 in County Kildare, Arthur inherited £100 at the age of 27 from his godfather, and three years later he set up business as a brewer. In 1759 he signed a 9,000 year lease on a disused brewery in St James Gate, Dublin where he began brewing porter and ale.

Porter is a dark, well-hopped beer made from brown malt. Its history is closely intertwined with that of stout, a term which originally referred to a beer’s strength but which now refers to the drink’s body and colour.

Today’s Guinness is a dry stout available in a number of variants and strengths, including Guinness Draught, Guinness Original/Extra Stout, Guinness Foreign Extra Stout, Guinness Special Export Stout and Guinness Bitter. It is nicknamed  ‘the black stuff’ on account of its dark colour, although it is actually a very dark shade of ruby!

Now brewed in 60 countries and available in over 120, the first Guinness export was to England in 1769 and by 1824 it had become a worldwide brand. Sales soared from 350,000 barrels in 1868 to over a million eighteen years later. However, by the 1970s sales were in decline and the company decided to make Guinness Extra Stout ‘more drinkable’, resulting in a brand re-launch in 1981 with pale malt being used for the first time.

Contemporary Guinness Draught and Extra Light Stout are weaker than their 19th Century counterpart, with Foreign Extra Stout and Special Export being closer to the original in character. Modern Guinness has a burnt flavour and is famous for its smoothness and thick, creamy head.

The production of Guinness continues to change with the times. In November last year the company announced plans to make their beer suitable for vegetarians and vegans by the end of 2016, through the introduction of a new filtration process that will avoid the need to use Isinglass from fish bladders.

Claims have been made in the past that Guinness can benefit the heart by slowing down the deposit of harmful deposits on artery walls. It has also been described as a ‘meal in a glass’, and at 198 calories per pint, has slightly fewer calories than skimmed milk, orange juice and most other light beers.

So, I wish you a happy St Patrick’s Day, filled with friends, fun, smiles and a glass of the black stuff!