Contrary to popular belief, the holiday is NOT the celebration of Mexico's independence (that'd be September 16, 1810).
Actually, it's not that big a deal in Mexico at all.
Cinco de Mayo commemorates the largely symbolic Mexican victory over the French at the Battle of Puebla in 1862. Though France still occupied the country for six years after that win, it was a great source of pride for Mexicans.
It was Chicano activists who brought the holiday to America in the 1960s, pointing to it as an example of indigenous Mexicans rejecting colonial rule.
Today, Americans have come to adopt the celebration. President Obama even makes a statement about it.
"Cinco de Mayo reminds us that America’s diversity is America’s strength," said Obama. "Today, as we celebrate the contributions and history of Mexican Americans and Hispanics in America, let us celebrate the larger story of America and our unique immigrant heritage."
However, some equate the love for the 5th of May to the popularity of St. Patrick's day: an excuse to get drunk on another culture's...alcohol.
Mexican-American writer and food expert Gustavo Arellano puts it more bluntly than that.
"I basically think Cinco de Mayo is one of the most pointless holidays ever created," Arellano told CNN's "In America" blog.
"I don’t celebrate it per se, I don’t look forward to it or wear a sombrero or go to a Mexican restaurant to go celebrate it. If people want to celebrate it, that’s fine, but I just think they are fools. When I say 'fools' I’m referring to Mexicans celebrating it because there is nothing to celebrate," he continued.
If you're still gung-ho on the fiesta, the Los Angeles Times has some recipes to get you in the...American spirit of things.