1. Three's company

St. Patrick used the shamrock as a symbol of the Christian church when he was spreading the word in Ireland. The leaves represent the Holy Trinity of God, Jesus and the Holy Spirit.

2. Shades of blue

Can you imagine a St. Patrick's Day in which people wore a little bit of blue instead of green? If not for the Irish Rebellion of 1798, it might have been the case. Saint Patrick's color a light shade of the hue that can still be seen on ancient Irish flags, but during the rebellion, the clover became a symbol of nationalism, and "wearing the green" spread from lapels to uniforms.

3. Driving snakes

Have you ever wondered how St. Patrick drove the snakes out of Ireland? The legend is actually a metaphor—there were no snakes to kick off of the island. By converting pagans to Christianity, St. Patrick drove "snakes" (non-Christians) from Ireland.

4. Location, location, location

St. Patrick wasn't Irish – he was actually born in Britain.

5. Drop the brew

Having a beer on St. Patrick's Day inside a real Irish bar is a recent invention. Though Ireland has been officially celebrating the holiday since 1903, it wasn't until the 1960s that anyone could celebrate with a drink at a bar. Because St. Patrick's Day falls during Lent, and Ireland is heavily Catholic, Ireland introduced a law forcing all of the pubs in the country to close on March 17 to prevent excessive partying during a holy time of year.

6. Going green(er)

In some ways, America is better at celebrating St. Patrick's Day than the Irish themselves. The first St. Patrick's Day parade wasn't held in Ireland but in colonies. In 1762 Irish soldiers serving in the English army celebrated by marching through the streets of New York City. By 1848, the event was made official and now attracts 3 million each year. In Chicago, the Chicago River has been dyed green since 1962, when sanitation workers began using green vegetable dye to liven up the water for a few hours.

7. To whom it may concern

Have you ever given anyone a St. Patrick's Day card? Hallmark says 12 million Americans give green-themed cards each year, with sales heaviest in New York City.

8. Will the real St. Patrick please stand up?

St. Patrick wasn't really named Patrick. His name was Maewyn Succat, though he changed his name to Patrick when he became a priest.