Saint Patrick (c. 385 – c. 461), the foremost patron saint of Ireland. Saint Patrick's Day, or the Feast of Saint Patrick, commemorates Saint Patrick and the arrival of Christianity in Ireland, and, by extension, celebrates the heritage and culture of the Irish in general. Initially, it was a religious observance, but it evolved into a secular celebration of Irish culture and heritage, particularly due to the Irish diaspora. It is now celebrated annually on March 17, in more than 200 countries. More