Easter, which celebrates Jesus Christ's resurrection from the dead, is Christianity's most important holiday. Easter is really an entire season of the Christian church year, as opposed to a single-day observance. Lent, the 40-day period leading up to Easter Sunday, is a time of reflection and penance and represents the 40 days that Jesus spent alone in the wilderness before starting his ministry, a time in which Christians believe he survived various temptations by the devil. The day before Lent, known as Mardi Gras or Fat Tuesday, is a last hurrah of food and fun before the fasting begins. The week preceding Easter is called Holy Week and includes Maundy Thursday, which commemorates Jesus' last supper with his disciples; Good Friday, which honors the day of his crucifixion; and Holy Saturday, which focuses on the transition between the crucifixion and resurrection. The 50-day period following Easter Sunday is called Eastertide and includes a celebration of Jesus' ascension into heaven.