Don your purple, green and gold, prepare to loosen your belts, and keep an ear out for that yearly trumpet blow: Today marks the beginning of Carnival in the United States, more commonly known as the Mardi Gras season.

It’s a joyous time but can be extremely confusing to the uninitiated, with good reason, as the only thing static about the season’s duration is that it begins on Jan. 6. How long it lasts is a much more complicated matter.

Here’s a primer.

Mardi Gras season begins on Jan. 6 because that is 12 days after Christmas. It’s known as King’s Day or the Epiphany in Christian tradition, a reference to a story in the Gospel of Matthew in which three Magi or wise men bring the infant Jesus (the referenced “king”) gifts of frankincense, gold and myrrh 12 days after his birth, as in the popular song.

It ends anywhere from 28 to 63 days later, determined by the date of Easter Sunday, which itself is determined by the first full moon after the spring equinox, otherwise known as the first day of spring. This year, Easter is April 16.

The culminating day of the season is called Fat Tuesday, on Feb. 28 this year.

Fat Tuesday, of course, is a day to party, because when that day is over, the gluttony comes to a crashing end with the beginning of Lent, a time to sacrifice and do without.

Most associate Mardi Gras with New Orleans, likely imagining a neck-breaking amount of beads, tables overloaded with food and booze, parades of marching bands and various colorful floats, and the unfortunate stereotype of bared flesh. In fact, much of the celebration in New Orleans is a family experience, not the Bourbon Street bacchanal that you see on TV.

While the Crescent City’s celebration has become the most popular of its kind in the United States, it’s far from the country’s only version.

It is probably not even its first.

In fact, many in Mobile, Ala., claim their home town was the original staging ground for Mardi Gras in the United States.

Some say the first Mardi Gras was celebrated in Mobile in 1830 (though, as CNN noted, the Mobile Area Chamber of Commerce argued it was 1703, a year after the city’s founding). As the story goes, the celebration made its way to New Orleans when the capital of the French Louisiana territory was moved from Mobile to New Orleans in 1718.

Others argue that it came to the Americas even earlier, in March of 1699. As CNN reported:

Legend has it that French explorer Pierre Le Moyne d’Iberville first introduced Mardi Gras to the area in 1699, after he sailed into the Gulf of Mexico on March 6 (Fat Tuesday), and set up camp on the west bank of the Mississippi river about 60 miles south of New Orleans. He named the site Point du Mardi Gras, in honor of the holiday which had been celebrated in Paris since the Middle Ages.

Mardi Gras is French for, surprise, Fat Tuesday.

That said, Louisiana remains the only state in which the day of revelry is a legal holiday.

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Of course, Carnival is celebrated around the world.

In Cologne, Germany, where it’s called the “fifth season of the year,” the season begins on the 11th day of the 11th month at 11:11 a.m. Each year, about 2 million people descend upon Rio de Janeiro to celebrate the holiday. The Danish celebration, called Fastelavn, includes children dressing up and gathering candy much like Halloween in the United States. In Spain, the celebration extends through Ash Wednesday, an eerily quiet day in cities such as New Orleans.

Carnival, though, probably predates any of the modern countries that celebrate it today. As with many Christian holidays, its roots may extend to paganism and tribal rituals.

Mardi Gras historian Arthur Hardy wrote:

Many see a relationship to the ancient tribal rituals of fertility that welcomed the arrival of Spring. A possible ancestor of the celebration was the Lupercalia, a circuslike orgy held in mid-February in Rome. The early Church fathers, realizing that it was impossible to divorce their new converts from their pagan customs, decided instead to direct them into Christian channels. Thus Carnival was created as a period of merriment that would serve as a prelude to the penitential season of Lent.

Though the exact origins of the holiday remain slightly obscure, what U.S. cities such as New Orleans, St. Louis, Mobile and Memphis can expect is certain: the parades.

Generally, private social aid and pleasure clubs, called “krewes,” hold the parades, which include large, paper-mache floats. Some krewes recycle floats each year, while others create new ones.

These often carry satirical political and social messages, an old tradition.

In 1877, for example, the New York Times reported that a Memphis krewe debuted a float called the “Vexed Eastern and Eternal Question” with “Turkey represented by an enormous turkey, with representatives of the different European powers anxious to take a slice with a sword.”

The floats carry masked riders who toss trinkets (think: plastic beads, metal doubloons and stuffed animals) to crowds screaming, “Throw me something, mister.”

That catchphrase is probably gendered because the first women’s parade did not hit the streets of New Orleans until 1941.

These parades are held throughout the season, and some new takes on the traditional form have appeared throughout the years. St. Louis, for example, hosts an annual pet parade filled with furry, four-legged friends.

To sustain themselves during all that parading, bacchants stuff themselves with king cake, a cinnamon-laden oval of dough topped with either fondant-like hardened sugar, granulated sugar in the season’s colors or both. Inside each cake, generally, is a small, plastic baby. Original cakes, though, contained a bean.

“A king cake is probably the one item on every table during Mardi Gras,” New Orleans restaurateur Ralph Brennan previously told this reporter for a Time story.

Hardy, the historian, said the cake began in 1870:

That year, revelers at a Carnival ball followed a centuries-old European custom: A giant cake with one golden bean and several silver beans hidden inside was cut, and slices were handed to the women. Whoever received the golden bean was named queen. Silver beans earned maid status.

(Luckily for those living outside the Gulf, many bakeries deliver the king cakes.)

The most important constant through all these traditions is celebration. Lent, after all, is always around the corner. So fill up on sweet cake and dance to some tunes. Fasting comes soon enough.

Happy Mardi Gras, y’all.

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