St Patrick's Day is one of the biggest celebrations around the world. It's marked by the Irish diaspora from the United States to Hong Kong, celebrating everything Irish on 17 March.
Here are 10 things you might not know about St Patrick's Day.
1. Although the colour green is normally associated with Ireland and St Patrick's Day, blue was considered symbolic of the country for many years. The Irish Presidential Standard remains blue to this day.
2. The very first St Patrick's Day parade took place in New York in the 1760s.
3. There are around 34.5 million Americans who list their heritage as either primarily or partially Irish.
4. One of the biggest parades takes place in New York City, which has a large Irish-born population.
5. One of the largest celebrations in the southern hemisphere takes place in Sydney, Australia. In 2010, the Sydney Opera House turned green to mark the 200th anniversary of St Patrick's Day - it was first marked there in 1810, when Lachlan Macquarie, the Governor of New South Wales, provided entertainment for Irish convict workers.
6. In Chicago, the Plumbers Local 110 union annually dyes the river green, which lasts around five hours.
7. St Patrick's Day folklore states the patron saint Patrick used the three leaves of a shamrock to explain the Christian holy trinity: the Father, the Son, and the Holy Spirit. However, experts states this tale was invented much later.
8. The birthplace of the patron saint of Ireland is actually unknown, but it is most likely to be in England, Wales or Scotland.
9. Patrick is said to have died on 17 March in the year 461.
10. St Patrick is also the patron saint of Nigeria, but the African country does not celebrate it as a national holiday.