Mardi Gras is both a day and a season. The season, called Carnival, always begins on Twelfth Night, for the 12th day after Christmas. The date is Jan. 6. +11.

Mardi Gras is the last and "biggest day of celebration," according to Mardi Gras New Orleans. Carnival celebrations begin on "Twelfth Night," also known as the Epiphany, which falls on Monday ...