Saint Patrick was born in England in 400 AD and was sold into slavery in Ireland for six years before escaping to France where he studied to become a priest. He later returned to Ireland to spread Christianity and used the shamrock to explain the Holy Trinity. Saint Patrick's Day is celebrated on March 17th and is a national holiday in Ireland where people traditionally wear shamrocks and engage in various activities. Common symbols of Saint Patrick's Day include the green shamrock, Blarney Stone, and leprechauns.