Ash Wednesday marks the beginning of the Season of Lent, a time for penance, fasting and self reflection which readies the soul for celebration of Christ's Resurrection on Easter Sunday. Lent is meant to allow the penitent to participate symbolically in the forty days fasting and temptation of Jesus in the desert which began his public ministry, and culminated in His crucifixion and resurrection. Consequentially, Ash Wednesday occurs forty six days prior to Easter Sunday. So why forty six days, and not forty? Sundays do not count during the Lenten season.
Ash Wednesday derives its name from the marking of an ashen cross on the forehead of the participant. The use of ashes as a symbol for repentance is an ancient tradition. Perhaps the most significant Biblically, considering Jesus referenced Jonah as a symbol of his death and resurrection, is the repentance of the Ninevites: "When the word reached the king of Nineveh, he arose from his throne, laid aside his robe from him, covered himself with sackcloth and sat on the ashes." (Jonah 3:6, NASB).
It is a popular misconception that Lent and Ash Wednesday are purely Catholic traditions, but this is not so. Anglicans, Lutherans, Presbyterians, Methodists, and even some Baptists celebrate some version.
The ashes and their treatment vary according to the liturgical tradition. In some, the palms from the previous Palm Sunday are burned and their ashes used. The ashes are mixed with water, Holy or otherwise, and/or oil, and applied ritually in various manners. Penitential psalms are read, particularly Psalm 51:
Have mercy upon me, O God, after Thy great goodness
According to the multitude of Thy mercies do away mine offences.
Wash me throughly from my wickedness: and cleanse me from my sin.
For I acknowledge my faults: and my sin is ever before me.
Against Thee only have I sinned, and done this evil in thy sight: that Thou mightest be
justified in Thy saying, and clear when Thou art judged.
Behold, I was shapen in wickedness: and in sin hath my mother conceived me.
But lo, Thou requirest truth in the inward parts: and shalt make me to understand wisdom
Thou shalt purge me with hyssop, and I shall be clean: Thou shalt wash me, and I shall be
whiter than snow.
Thou shalt make me hear of joy and gladness: that the bones which Thou hast broken may
Turn Thy face from my sins: and put out all my misdeeds.
Make me a clean heart, O God: and renew a right spirit within me.
Cast me not away from Thy presence: and take not Thy Holy Spirit from me.
O give me the comfort of Thy help again: and stablish me with Thy free Spirit.
Then shall I teach Thy ways unto the wicked: and sinners shall be converted unto Thee.
Deliver me from blood-guiltiness, O God, Thou that art the God of my health: and my
tongue shall sing of Thy righteousness.
Thou shalt open my lips, O Lord: and my mouth shall shew Thy praise.
For Thou desirest no sacrifice, else would I give it Thee: but Thou delightest not in
The sacrifice of God is a troubled spirit: a broken and contrite heart, O God, shalt Thou
O be favourable and gracious unto Sion: build Thou the walls of Jerusalem.
Then shalt Thou be pleased with the sacrifice of righteousness, with the burnt-offerings
and oblations: then shall they offer young calves upon Thine altar.
-- Psalm 51, from The Book of Common Prayer
Other traditions have grown up around Ash Wednesday. In the days preceding Lent, meat and other rich foods had to be disposed of, and so evolved the tradition of the Carnival, a festival which preceded the season of Lent. The most famous of these, particularly in North America, is Mardi Gras, named after the last day of the festivities (Mardi Gras means literally, in French, "Fat Tuesday"). In other traditions, the Tuesday before Ash Wednesday, Shrove Tuesday, is known as "Pancake Tuesday", because the making of pancakes were a convenient means of using up stores of dairy products (milk and eggs) which are forbidden during the Lenten season.