Why green? Why shamrocks? Who's Saint Patrick? Read our list and find out everything you need to know to understand what the merriment is about. Oh, and don't forget to wear green on Saint Patrick's Day to avoid the traditional pinch!

1. Saint Patrick
Saint Patrick, known as the Apostle of Ireland, was a high-ranking Christian clergyman. His legendary use of the shamrock as an illustration of the Trinity led to its adoption as Ireland's national symbol.

2. Ireland
Ireland was Christianized by Saint Patrick in the 5th century. He and his successors founded churches and monasteries that became centers of Christian art and refinement. Saint Patrick's Day is the most important national holiday in Ireland.

3. Feast Day
Saint Patrick's Day, March 17, is the traditional feast day of Ireland's patron saint. In the United States, Saint Patrick's Day has evolved into a celebration of Irish American heritage. Many Irish American communities hold parades, with celebrants dressed in green to symbolize the lush Irish landscape. Some people take it a bit further and dye their hair and food green, and some communities (such as Chicago) go so far as to pour green dye into rivers, lakes, and other bodies of water.

4. Shamrocks
Shamrocks have been considered good-luck symbols by the Irish since early times, and shamrocks or various representations of the plant are frequently worn on Saint Patrick's Day. The hop clover is widely accepted as the original shamrock picked by Saint Patrick. The name shamrock comes from the Irish Seamrog, which means "little clover."

5. Leprechauns
In Irish folklore, leprechauns (Old Irish for "small bodies") are mischievous little old men. These elves, who work as cobblers, are believed to know where gold is hidden.

6. Rainbows
Does tracking down a leprechaun and his hidden pot of gold sound improbable at best? Many people believe that the leprechaun keeps his gold at the end of a rainbow. Have you ever seen the end of a rainbow? Interestingly, one of the definitions of rainbow is "a goal, hope, or ideal that is unlikely to be achieved or realized."

Also on Encarta
Find out what else March 17th is known for.

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