Across the country, people will don green clothing today and make plans to imbibe some green beer or feast on bangers and mash (or, mistakenly, Lucky Charms) to celebrate St. Patrick's Day.

Parades commemorating the day will take place in 30 countries, including a weeklong festival on the Caribbean island of Montserrat. The island of more than 5,000 people will celebrate its Irish heritage as well as an unsuccessful slave uprising that had been planned for March 17, 1768.

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No matter how you plan to celebrate, brush up on your St. Paddy's Day knowledge by reviewing these key facts about the holiday.

1. The real St. Patrick we know today was known in the third century as Maewyn, a young man who spurned his British family's Christian faith. After being captured by Irish pirates at the age of 16, Maewyn's faith was reborn. He eventually reunited with his family and then heard God's calling to go to Ireland as an early Christian missionary. He took the Latin name Patricius upon his ordination, which became St. Patrick (although he has never been formally canonised by a Pope). He is believed to have died on March 17.

2. St. Patrick was initially depicted wearing blue, not green. Green became associated with the holiday after the Irish independence movement in the late 18th century.

3. The Saint Patrick's Day Parade in New York City only allows marchers on foot. No modern conveniences are allowed. The first NYC parade took place in 1762 and featured many homesick, Irish ex-patriots who reveled in the opportunity to wear green (which was banned in Ireland) and sing Irish songs.

4. You might hear some people talking about "Erin go Bragh" today. That phrase is a derivative of "Irish Éirinn go Brách," which translates to "Ireland Forever."

5. Shamrocks are associated with the holiday because legend says St. Patrick used the three-leafed plant to explain the concept of the Holy Trinity during his Christian missionary work. However, shamrocks were often worn in Ireland as a symbol of the cross. In addition, the Irish flag - made of equal sections of green, white and orange - represents Catholics (green) and Protestants (orange) and peace (white) between the two groups.

6. Corned beef is a staple on St. Patrick's Day that gets its name from the coarse "corns" or pellets of salt required to cure the meat.

7. Drinking wasn't always a favorite way of celebrating St. Patrick's Day. In fact, from 1903 to 1970, the holiday was a religious observance marked by the closure of all pubs.