St. Patrick's Day - celebrated worldwide by Irish people and increasingly by many of non-Irish descent (Usually in the US and Ireland) hence the phrase "Every one is Irish on St. Patrick's day". Celebrations are generally themed around all things green and Irish; both Christians and non-Christians celebrate the secular version of the holiday by wearing green, eating Irish food, imbibing Irish drink, and attending parades.
Each year on the Saturday before March 17, the Chicago river runs emerald green in celebration of this annual holiday. The dye used is actually "orange" in color, but when mixed with the natural color of the river it becomes almost fluorescent green for several hours.
Saint Patrick's Day, colloquially Paddy's Day or St. Patty's Day, is the feast day which annually celebrates Saint Patrick (373-493), the patron saint of Ireland, on March 17.
