The Mardi Gras celebrations in New Orleans (and beyond) will be at full tilt on Tuesday, but the revelry turns to austerity the following day, known as Ash Wednesday, for Christians marking the beginning of Lent. During the 40-day period of fasting, prayer and repentance in preparation for Easter, Christians strive to imitate Jesus Christ’s actions and reflect on his life, death and resurrection.

This year Lent begins on Feb. 18 and ends on April 2 -- technically 46 days, but Sundays are not included in the count since they are considered a day of worship and rest.

For those unfamiliar with Lent and how it is observed, below are three answers to common questions surrounding the Lenten fast:

How is Lent observed?

Christians started observing Lent in the fourth century, with strict self-denial and self-examination marking the period. A central practice of fasting included the exclusion of luxury foods like meat, dairy products and eggs.

Today, Catholics refrain from eating meat on Fridays during Lent. Eastern Orthodox Christians follow stricter fasting rules where no meat, eggs or dairy products are allowed. Fish is permitted on the Feast of the Annunciation on March 25 and on Palm Sunday, March 29.

Besides fasting, Christians may also voluntarily refrain from "bad" habits during the 40-day period – anything from eating chocolate to watching TV -- as a way to imitate Christ’s life.

Other Christian denominations including Lutherans, Methodists, Presbyterians and Anglicans also observe Lent. Eastern Orthodox churches start their Lent observances 40 days before Palm Sunday, with fasting continuing during the Holy Week of Orthodox Easter on April 12.

Why is Lent 40 days long?

Historically, Lent was referred to as Quadragesima – the Latin word for forty. According to catechism of the Roman Catholic Church, the Lenten fast is 40 days to represent the 40 days Jesus Christ spent fasting in the desert after he was baptized by John the Baptist.

While Lent is 40 days long, there can be as many as 46 days between Ash Wednesday and Easter, depending on the year. This stems from the Christian belief that Sunday is a day of rest. When Lent was first observed, the church removed Sundays entirely from the Lenten restrictions, making it a 34-day fast. In the fifth century, Christians wanted to make the fast 40 days, which required two steps. At first they added Good Friday and Holy Saturday to make it 36 days. Within the next few centuries, Ash Wednesday was added as well as the Thursday, Friday and Saturday before the first Sunday of Lent, bringing the total fasting days to 40.

What is Ash Wednesday?

Ash Wednesday, this year falling on Feb. 18, marks the beginning of Lent. While many see the observance as a Catholic one, most denominations that follow a calendar-based liturgy also observe Ash Wednesday. This includes Lutheran, Methodist, Presbyterian and Anglican denominations. During services, clergy use ashes burned at last year’s Palm Sunday to mark a cross on member’s foreheads as they bow, meant to signify the Biblical passage in Genesis 3:19: “For dust you are and to dust you shall return.”