The terms "Mardi Gras" (pron-en?m?rdi?r??), "Mardi Gras season", and "Carnival season", in English (English language), refer to events of the Carnival celebrations, beginning on or after Epiphany (Epiphany (holiday)) and ending on the day before Ash Wednesday. Mardi Gras is French for "Fat Tuesday" (in ethnic English tradition, Shrove Tuesday), referring to the practice of the last night of eating richer, fatty foods before the ritual fasting of the Lenten season, which started on Ash Wednesday. Related popular practices were associated with celebrations before the fasting and religious obligations associated with the penitential season of Lent. Popular practices included 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". The festival season varies from city to city, as some traditions consider Mardi Gras the entire period between Epiphany (Epiphany (holiday)) or Twelfth Night (Twelfth Night (holiday)) and Ash Wednesday. Others treat the final three-day period before Ash Wednesday as the Mardi Gras. In Mobile (Mardi Gras in Mobile), Alabama, Mardi Gras-associated social events begin in November, followed by mystic society balls on Thanksgiving, then New Years 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 Years Day. Other cities famous for Mardi Gras celebrations include Rio de Janeiro in Brazil, Quebec City, Quebec in Canada; Mazatlan in Mexico; and New Orleans, Louisiana in the United States. Many other places have important Mardi Gras celebrations as well.

Carnival is an important celebration in Catholic European nations. In the United Kingdom and Ireland, the week before Ash Wednesday is called "shrovetide", ending on Shrove Tuesday. It has its popular celebratory aspects as well. Pancakes are a traditional food. Pancakes and related fried breads or pastries made with sugar, fat and eggs are also traditionally consumed at this time in many parts of Latin America and the Caribbean (Caribbean Carnival).