Mardi Gras refers to events of the Carnival celebration, beginning on or after the Christian feasts of the Epiphany (Three Kings Day) and culminating on the day before Ash Wednesday (known as Shrove Tuesday). Mardi Gras is French for "Fat Tuesday", reflecting the practice of the last night of eating rich, fatty foods before the ritual fasting of the Lenten season.

Related popular practices are associated with Shrovetide celebrations before the fasting and religious obligations associated with the penitential season of Lent. In countries such as the United Kingdom, Mardi Gras is also known as Shrove Tuesday, which is derived from the word shrive, meaning "to administer the sacrament of confession to; to absolve".

Mardi Gras, as a celebration of life before the more-somber occasion of Ash Wednesday, nearly always involves the use of masks and costumes by its participants. In New Orleans, for example, these often take the shape of fairies, animals, people from myths, or various Medieval costumes as well as clowns and Indians (Native Americans). However, many costumes today are simply elaborate creations of colored feathers and capes. Unlike Halloween costumery, Mardi Gras costumes are not usually associated with such things as zombies, mummies, bats, blood, and the like, though death may be a theme in some. The Venice tradition has brought golden masks into the usual round of costumes.

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