Shrove Tuesday is the day before Lent starts: the Tuesday before Ash Wednesday. It's a day of penitence, to clean the soul, and a day of celebration as the last chance to feast before Lent begins.
Shrove Tuesday is sometimes called Pancake Day after the fried batter recipe traditionally eaten on this day.
But there's more to Shrove Tuesday than pigging out on pancakes or taking part in a public pancake race. The pancakes themselves are part of an ancient custom with deeply religious roots.
Penitence
Shrove Tuesday gets its name from the ritual of shriving that Christians used to undergo in the past. In shriving, a person confesses their sins and receives absolution for them.
When a person receives absolution for their sins, they are forgiven for them and released from the guilt and pain that they have caused them.
In the Catholic or Orthodox context, the absolution is pronounced by a priest.
Shrove Tuesday celebrations
Shrove Tuesday is a day of celebration as well as penitence, because it's the last day before Lent.
Lent is a time of abstinence, of giving things up. So Shrove Tuesday is the last chance to indulge yourself, and to use up the foods that aren't allowed in Lent.
Giving up foods: but not wasting them
During Lent there are many foods that some Christians - historically and today - would not eat: foods such as meat and fish, fats, eggs, and milky foods.
So that no food was wasted, families would have a feast on the shriving Tuesday, and eat up all the foods that wouldn't last the forty days of Lent without going off.
The need to eat up the fats gave rise to the French name Mardi Gras ('fat Tuesday'). Pancakes became associated with Shrove Tuesday as they were a dish that could use up all the eggs, fats and milk in the house with just the addition of flour.