Ireland: Saint Patrick's Day or the Feast of Saint Patrick is a cultural and religious holiday celebrated on 17 March. It is named after Saint Patrick (c. AD 385–461), the most commonly recognised of the patron saints of Ireland.

Saint Patrick's Day was made an official Christian feast day in the early seventeenth century and is observed by the Catholic Church, the Anglican Communion (especially the Church of Ireland), the Eastern Orthodox Church and Lutheran Church. The day commemorates Saint Patrick and the arrival of Christianity in Ireland, as well as celebrates theheritage and culture of the Irish in general. Celebrations generally involve public parades and festivals, céilithe, and the wearing of green attire or shamrocks. Christians also attend church services, and the Lenten restrictions on eating and drinking alcohol are lifted for the day, which has encouraged and propagated the holiday's tradition of alcohol consumption.

Originally, the color associated with Saint Patrick was blue. Over the years the color green and its association with Saint Patrick's Day grew. Green ribbons and shamrocks were worn in celebration of St Patrick's Day as early as the 17th century. Saint Patrick is said to have used the shamrock, a three-leaved plant, to explain the Holy Trinityto the pagan Irish, and the ubiquitous wearing and display of shamrocks and shamrock-inspired designs has become a feature of the day. (source: Wikipedia)

 'When Irish eyes are smiling'