Is it a day off?
An observance: marked in the calendar, but not a day off.
In 2033 it falls on a Thursday, a working day.
Fixed date: it is on the same day of the year every year (Mar 17).
Saturday and Sunday · A public holiday does not always close every business. Essential services, shops and some industries keep working, and pay rules differ by country and contract.
Saint Patrick's Day
Saint Patrick's Day is the national day of Ireland and the feast day of Saint Patrick, the fifth-century missionary who is the most widely venerated patron saint of the country. According to tradition he was born in Roman Britain, was captured and brought to Ireland as a slave, escaped, and returned later as a bishop to spread Christianity. He is said to have used the three-leaved shamrock to explain the Trinity. The feast day is also a patron saint's day for the Church of Ireland and the Catholic Church alike.
In Ireland the day combines a religious feast with a national celebration, with Mass in the morning and parades, concerts and festivals in towns and cities, including a large multi-day festival in Dublin. Green clothing, shamrocks and flags are everywhere. The day is celebrated even more widely among the Irish diaspora, with large parades in New York, Boston, Chicago and many other cities, and landmarks around the world are lit in green. Smaller towns hold their own parades, often with local bands and community floats. Visitors should expect large crowds in Dublin.
Saint Patrick's Day: all countries