It's the big hurrah before Christians start Lent, a season of prayer, penance and fasting in preparation for the Easter season.
But even on a day with king cake, beads, parades and giant floats, there's still a question about the celebration: Why are pancakes being served?
It started when Pope St. Gregory prohibited Christians from eating all forms of meat and animal products during Lent around A.D. 600.
He told St. Augustine of Canterbury, a founder of the Christian church in southern England, to enforce those same fasting rules in England.
So Christians made pancakes to use up their supply of eggs, milk and butter in preparation for Lent.
When the tradition spread throughout Europe, people in France followed the trend. They made waffles, crepes and a dessert many know as king cake to utilize their dairy products. They called it Mardi Gras.
And the English named it Pancake Day.