Fat Tuesday, also known as Mardi Gras, is a celebration that takes place on the day before Ash Wednesday, which marks the beginning of the Lenten season. The name "Fat Tuesday" comes from the tradition of eating rich, fatty foods on this day before the ritual sacrifices and fasting of the Lenten season. The celebration is also known as Shrove Tuesday, Carnival Tuesday, or Pancake Tuesday, depending on the location.

The history of Fat Tuesday is rooted in Christianity, and the day has different names and traditions in different countries. In the UK, it is known as Pancake Day, and pancakes are eaten to use up ingredients such as eggs, milk, and butter before the fasting period of Lent begins. In Italy, it is called Martedì Grasso (Fat Tuesday) and is the main day of Carnival.

Fat Tuesday is a day of revelry and festivities, with people coming together to enjoy sumptuous meals, delicious treats, and vibrant parades. In some cultures, the person who finds a trinket or baby figurine baked inside a cake is crowned king or queen of the Carnival, a distinction that carries various duties depending on the culture.

Overall, Fat Tuesday is a time for celebration and indulgence before the penitential period of fasting and abstinence during Lent begins on Ash Wednesday.