Where Easter celebrates the resurrection of Jesus Christ after his death on the Cross, Lent is concerned with the events leading up to and including Jesus' execution by Rome. This took place around the year 29 of the Common Era in Roman occupied Jerusalem of Palestine.
There are traditionally 40 days in Lent which are marked by fasting from foods or festivities, and other acts of penance. Lent is a season of sorrowful reflection that is punctuated by breaks in the fast on Sundays (the day of the resurrection). Sundays are not counted in the 40 days of Lent. Because Lent is a season of grief that necessarily ends with a great celebration of Easter, it is known in Eastern Orthodox circles as the season of "Bright Sadness".
Though originally of pre-Christian content, the traditional carnival celebrations that precede Lent in many cultures, have become associated with the season of fasting if only because they are a last opportunity for excess before Lent begins. The most famous of pre-lenten carnivals in the West is Fat Tuesday or Mardi Gras.
Fasting during Lent was in ancient times more severe than it is today. Meat, fish, eggs and milk products were strictly forbidden, and only one meal was taken each day. Today, in the West, the practice is considerably relaxed, though in the Eastern church, abstinence from the above mentioned food products is still commonly practiced. Lenten practices (as well as other liturgical practices) are more common in protestant circles than they once were.
Fasting during Lent is a way for the Christian to identify with Jesus in his suffering, which according to the record in the New Testament Biblical writings known as the Gospels he underwent for the sake of humans, in order to take make propitiation for their failure to keep the laws instituted by Yahweh (the self-chosen name of God in the Judeo-Christian tradition). This sacrifice is referred to by Christians variously as a substitutionary death, a redemptive death, and a death that satisfied the perfect justice of God, who actually provided the means for the satisfaction by sending Jesus, said in the Bible to be God's own son, to die in place of humanity. It is this distinction that fulfills the Hebrew's hope for a messiah (Christ, in Greek) who would save the troubled nation, according to the New Testament writings.
There are several Holy days within the season of Lent. Ash Wednesday is the first day of Lent. The central symbol of that day is the ash with which Catholics mark foreheads of the people. Ash is a traditional symbol of mourning, appearing throughout the Biblical writings and representing the dust from which God created humanity and the dust to which humanity is destined to return. Palm Sunday is the day that Jesus entered Jerusalem as the "King of the Jews". His entry was marked by celebrations among his followers and many of the residents of Jerusalem, though it represented a major threat to the religious leaders and to Rome. Yet, Jesus' method of entry was symbolic for the purpose of his coming. Entering not on a war horse, but on a donkey (a symbol of peace), he foreshadowed that he would not accomplish his mission through violence, but through sacrifice. Maundy Thursday is the Thursday of the "Last Supper" shared by Jesus with his disciples, during which he gave a "Mandatum Novuum" or "New Commandment" (whence, 'Maundy Thursday') that the disciples "love one another" as Jesus loved them. Good Friday is the day that Jesus was crucified. He died on this day and was buried.
Palm Sunday also begins the Passion Week, or the week of Jesus' suffering. The week (and the season of Lent) ends with Easter Sunday and the celebration of the resurrection of Jesus.
See also: Quinquagesima