Mardi Gras History:

There are many mysteries and myths surrounding the tradition of Mardi Gras (also known as Shrove Tuesday and Fat Tuesday). 
The carnival season starts on epiphany (Twelfth Night) and lasts until Ash Wednesday and the dawn of the Lenten season.  The word carnival comes from the latin carne meaning meat, thus translated it means shedding the flesh or "farewell to the flesh." 

The evening of January 6th was chosen as the start of carnival because Epiphany notes the end of the traditional twelve days of the Christmas Season.  Despite what the retailers might have you believe, the period leading up to sunset Christmas Eve is NOT the Christmas Season but rather Advent or the coming.  The Christmas Feast ends on the twelfth day of the season, heralding the arrival of the Three Wise Kings at the stable in Bethlehem.

Carnival itself is a mid-winter festival that certainly has some pagan roots.  In ancient Europe, this time was seen as one to enjoy neighborly visits and pleasures since the harvest was over and next year's crop was yet to be planted.  Additionally, short days, long nights and the cold weather of winter led people to look for celebrations in their lives.  Just as Christianity embraced the solstice traditions of pagans in the Christmas celebration, the early Catholic church embraced some aspects of the pagan celebrations leading up to Lent.

Mardi Gras is the culmination of the Carnival Season.  Ash Wednesday starts the traditional season of penance, so the final "farewell to the flesh" occurs on Mardi Gras day.  Mardi Gras is a french phrase meaning Fat (gras) Tuesday (mardi).

------------------
"What a waste it is to lose one's mind. Or not to have a mind is being very wasteful. How true that is.".............
Dan Quayle