Saint Patrick’s day (Saint Patty’s Day) is an international religious and cultural holiday celebrated on march 17. Saint Patrick’s day is a celebration of Saint Patrick, a Catholic Patron Saint of Ireland, and the arrival of Catholicism in Ireland. It is celebrated by most Christian churches around the globe. Wearing of shamrocks and other green attire is the most popular way to recognize the day. Saint Patrick’s Day is a public holiday in the Republic of Ireland, Northern Ireland, Newfoundland and Labrador and on the island of Montserrat.