For people who live in Ireland and Northern Ireland it is a national holiday, but in the wider world it is seen as an opportunity to explore one of the most emblematic aspects of Irish culture – getting boozed up.

The preferred tipple for most people on St Patrick’s Day is a pint of Irish stout, a heavy, black beer, although others may plump for a glass of Irish whiskey.

Like the Chinese, the Irish have a long history of economic migration, and have settled in many countries around the world, particularly in the USA.

Because of their large populations of people of Irish descent, cities like New York and Boston have enormous St Patrick’s Day parades, where hundreds of thousands of marchers and millions of spectators parade through the city.

The colour green is predominant on St Patrick’s Day as that is the national colour of Ireland, which is sometimes called the Emerald Isle.

As any traveller knows, Ireland is a very green, rural country, thanks to the amount of rainfall, with some areas seeing rain for 225 days in a year.

This year even the President of the United States joined in the fun by adding green dye to the fountains in the White House gardens.

But the American city of Chicago goes even further; since 1961 the Chicago River has been dyed green on St Patrick’s Day.

The tradition began by accident after a plumber, who was using dye to detect leaks into the river, discovered his orange dye turned green when mixed with water.

City officials decided to add dye to the river to celebrate St Patrick’s Day, however during the first attempt they used too much dye and turned the river bright green for a week.