(CNN) -- Every March 17, the world suddenly looks a bit greener as people don the color to celebrate St. Patrick's Day. From shamrocks and leprechauns to corned beef and green beer, here's what you need to know about the holiday.
What is St. Patrick's Day?
St. Patrick's Day is the feast day of St. Patrick, who is the patron saint of Ireland. In addition to its religious roots, the holiday has become synonymous with the color green, shamrocks and festive drinking.
Who was St. Patrick?
St. Patrick was a Christian missionary who converted the Irish people to Christianity.
He was born in Britain in 385 AD and brought to Ireland as a slave when he was 16. Six years later, he escaped to a French monastery, became a priest and returned to Ireland to spread the teachings of Christianity.
Legend says that he also drove the snakes out of Ireland. However, biologists say there were never any snakes in Ireland in the first place.
How do people celebrate?
St. Patrick's Day is primarily celebrated as a religious holiday in Ireland. Banks, stores and businesses shut down for the national holiday. Traditionally, the Irish go to church in the morning and pray for missionaries. Drinking, dancing and music are also part of the festivities later in the day.
Most of the US celebrates the occasion as a secular holiday. The first St. Patrick's Day celebration in America was held in Boston in 1737. Today, there are huge parades in New York City, Chicago and Savannah, Georgia, as well.
Although the traditional meal eaten on the holiday in Ireland is lamb or bacon, Irish-Americans eat corned beef and cabbage.
Why are there shamrocks everywhere?
Legend has it that St. Patrick used a three-leaf clover, otherwise known as a shamrock, to explain the concept of the Holy Trinity to pagans. Shamrocks are also the national flower/emblem of Ireland.
Why is everything green?
The original color of St. Patrick's Day was actually blue. But over time, green won out.
The color green is a nod to Ireland's nickname, the Emerald Isle.
Wearing green on St. Patrick's Day is supposed to prevent you from getting pinched by a leprechaun. Leprechauns are tricky mythical fairies in Irish folklore who like to pinch anyone in sight. However, legend says that wearing green makes you invisible to these feisty creatures.
The color is also politically symbolic. Green is associated with the Irish nationalist movement against the English crown in the 1600s. And when Irish immigrants came to America, they wore green to show pride for their home country.
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