Saint Patrick's Day (Irish: Lá ’le Pádraig or Lá Fhéile Pádraig), colloquially St. Paddy's Day or Paddy's Day, is an annual feast day which celebrates Saint Patrick (circa AD 385–461), one of the patron saints of Ireland, and is generally celebrated on March 17.
The day is the national holiday of Ireland. It is a bank holiday in Northern Ireland and a public holiday in the Republic of Ireland and Montserrat. In Canada, Great Britain, Australia, the United States, and New Zealand, it is widely celebrated but is not an official holiday.
St. Patrick's feast day was placed on the universal liturgical calendar in the Catholic Church due to the influence of the Waterford-born Franciscan scholar Luke Wadding in the early part of the 17th century, although the feast day was celebrated in the local Irish church from a much earlier date. St. Patrick's Day is a holy day of obligation for Roman Catholics in Ireland. The feast day usually falls during Lent; if it falls on a Friday of Lent (unless it is Good Friday), the obligation to abstain from eating meat can be lifted by the local bishop. The church calendar avoids the observance of saints' feasts during certain solemnities, moving the saint's day to a time outside those periods. St. Patricks Day is very occasionally affected by this requirement. Thus when March 17 falls during Holy Week, as in 1940 when St. Patrick's Day was observed on April 3 in order to avoid it coinciding with Palm Sunday, and again in 2008, having been observed on 15 March.
(From Wikipedia, the free encyclopedia)