The terms "Mardi Gras" ( /ˈmɑrdiɡrɑː/), "Mardi Gras season", and "Carnival season",^{[1][2][3][4][5]} in English, refer to events of the Carnival celebrations, beginning on or after Epiphany and culminating on the day before Ash Wednesday. Mardi gras is French for Fat Tuesday, referring to the practice of the last night of eating richer, fatty foods before the ritual fasting of the Lenten season, which begins on Ash Wednesday; in English the day is sometimes referred to as Shrove Tuesday, from the word shrive, meaning "confess."^[6] Related popular practices are associated with celebrations before the fasting and religious obligations associated with the penitential season of Lent. Popular practices include wearing masks and costumes, overturning social conventions, dancing, sports competitions, parades, etc. Similar expressions to Mardi Gras appear in other European languages sharing the Christian tradition. In English, the day is called Shrove Tuesday, associated with the religious requirement for confession before Lent begins.

In many areas, the term "Mardi Gras" has come to mean the whole period of activity related to the celebratory events, beyond just the single day. In some US cities, it is now called "Mardi Gras Day" or "Fat Tuesday".^{[1][2][3][4][5]} The festival season varies from city to city, as some traditions consider Mardi Gras the entire period between Epiphany or Twelfth Night and Ash Wednesday.^[7] Others treat the final three-day period before Ash Wednesday as the Mardi Gras.^[8] In Mobile, Alabama, Mardi Gras-associated social events begin in November, followed by mystic society balls on Thanksgiving,^[7][9] then New Year's Eve, followed by parades and balls in January and February, celebrating up to midnight before Ash Wednesday. In earlier times parades were held on New Year's Day.^[7] Other cities famous for Mardi Gras celebrations include Rio de Janeiro, Brazil; Barranquilla, Colombia; Port of Spain, Trinidad and Tobago; Quebec City, Canada; Mazatlán, Sinaloa, Mexico; and New Orleans, Louisiana, United States.

Shrove Tuesday (also known as Pancake Tuesday, Pancake Day, Mardi Gras, and Fat Tuesday) is the day preceding Ash Wednesday, the first day of Lent. Shrove Tuesday is observed mainly in English speaking countries,^{[citation needed]}, but is also observed in the Philippines and Germany. Shrove Tuesday is linked to Easter, so its date changes on an annual basis.

In most traditions the day is known for the eating of pancakes before the start of Lent. Pancakes are eaten as they are made out of the main foods available, sugar, fat, flour and eggs, the consumption of which was traditionally restricted during the ritual fasting associated with Lent.