It is observed by the Catholic Church, the Anglican Communion, the Eastern Orthodox Church and Lutheran Church.
Saint Patrick's Day was made an official feast day in the early seventeenth country, and has gradually become a celebration of Irish culture in general.
The day is generally characterized by the attendance of church services, wearing of green attire, public parades and processions, the lifting of Lenten restrictions on eateng and drinking alcohol.
Saint Patrick's Day is a public holiday in the Republic of Ireland, Northern Ireland, Newfoundland and Labrador, Montserrat. It is also widely celebrated by the Irish diaspora, especially in places such as Great Britain, Canada, the United States, Argentina, Australia, and New Zealand.
Source is Wikipedia.