St. Patrick's Day is celebrated every year on March 17 (Credit: Hongreddotbrewhouse/ CC-BY-SA-3.0/ Wikimedia.org)

St. Patrick's Day, celebrated annually on March 17, is a lively holiday that honors the most famous of Ireland's three patron saints. Though widely known for its parades, shamrocks, and everything green, the day's roots are steeped in history.