Mardi Gras itself falls on Shrove Tuesday - the Tuesday before Ash Wednesday, the start of the season of Lent in the Christian calendar. The name Mardi Gras translates literally as "Fat Tuesday", marking a final day of celebration before the solemn 40 days of prayer and fasting during the period of Lent.
The celebration of Mardi Gras in Europe may have had it's roots in the ancient revelries. The Mardi Gras traditions in Christian Europe date back to the early days of the Roman Catholic church. It is believed to have first been celebrated in the United States in 1699.
Mardi Gras festivities, along with those of the Brazilian Carnival, actually begin after Epiphany (the end of the Christmas season) and are marked with parades, king cakes, masked balls and a number of other traditions, some old some new. The parades and balls are sponsored by private social organizations known as Krewes.
You'll see a lot of purple, green and yellow at Mardi Gras celebrations. These are the official colors of Mardi Gras, symbolizing Justice (purple), Faith (green) and Power (yellow).