Saint Patrick's Day is a cultural and religious holiday observed annually on March 17, the traditional death date of its namesake, the foremost patron saint of Ireland. Initially established as a Christian feast day in the early 17th century, it commemorates the arrival of Christianity in Ireland. The observance has since evolved to more broadly celebrate Irish heritage and culture. It is an official public holiday in the Republic of Ireland, Northern Ireland, the Canadian province of Newfoundland and Labrador, and the British Overseas Territory of Montserrat.
The historical figure central to the day was a 5th-century Romano-British missionary and bishop credited with converting Ireland to Christianity. Key legends associated with him include using the three-leaf shamrock to explain the Holy Trinity, which has become a primary symbol of the holiday. The transformation of the observance from a solemn religious event into a large-scale secular celebration was significantly influenced by the Irish diaspora, particularly in North America. The first parades celebrating the day were held not in Ireland but in cities like Boston and New York in the 18th century, serving as a public display of Irish identity and solidarity.
Modern celebrations are widely characterized by public parades, festivals known as cilithe, and the wearing of green attire or shamrocks. While it remains an important feast day within Christian denominations, it is now largely a global festival of Irish culture. The tradition of lifting Lenten restrictions on eating and drinking for the day has contributed to its contemporary association with public revelry. This dual nature as both a religious commemoration and a secular cultural celebration allows for its widespread observance by people of both Irish and non-Irish descent worldwide.
