At Masses and services of worship on this day, ashes are imposed on the foreheads (or tonsure spots, in the case of some clergy) of the faithful. The priest, minister, or in some cases officiating layperson marks the forehead of each participant with black ashes in the shape of a cross, which the worshiper traditionally retains until washing it off after sundown. The act echoes the ancient Near Eastern tradition of throwing ash over one's head to signify repentance before God (as related in the Bible). The priest or minister says one of the following when applying the ashes:
Remember, O man, that you are dust, and unto dust you shall return. (Latin: Memento homo, quia pulvis es, et in pulverem reverteris.)—Genesis 3:19
Turn away from sin and be faithful to the Gospel.—Mark 1:15
Repent, and hear the good news.—Mark 1:15
The ashes used in the service of worship or Mass are sacramentals, not a sacrament. The ashes may be prepared by burning palm leaves from the previous year's Palm Sunday celebrations. They are blessed according to various rites proper to each liturgical tradition, sometimes involving the use of Holy Water. In some churches they are mixed with light amounts of water or olive oil which serve as a fixative.
In some of the free church liturgical traditions, other practices are sometimes added or substituted, as other ways of symbolizing the confession and penitence of the day. For example, in one common variation, a small card or piece of paper is distributed to the congregation on which a person is invited to write a sin she/he wishes to confess. These small cards are brought forth to the altar table where they are burned.
In the Roman Catholic Church, ashes, being sacramentals, may be given to any Christian  as opposed to Catholic sacraments, which are generally reserved for church members (except in cases of grave necessity). Similarly, in most other Christian denominations ashes may be received by all who profess the Christian faith and are baptized
In the Roman Catholic Church, Ash Wednesday is observed by fasting, abstinence from meat, and repentance—a day of contemplating one's transgressions. The Anglican Book of Common Prayer also designates Ash Wednesday as a day of fasting. In other Christian denominations these practices are optional, with the main focus being on repentance. On Ash Wednesday and Good Friday, Roman Catholics between the ages of 18 and 59 are permitted to consume only one full meal, which may be supplemented by two smaller meals, which together should not equal the full meal. A significant portion of Roman Catholics known as Traditionalists will go beyond the minimum obligations demanded by the Church and undertake a complete fast or a bread and water fast. Ash Wednesday and Good Friday are also days of abstinence from meat (for those Catholics age 14 and over), as are all Fridays in Lent. Traditional Roman Catholics continue fasting during the whole of Lent, as was the Church's traditional requirement, concluding only after the celebration of the Easter Vigil.
As the first day of Lent, it comes the day after Shrove Tuesday or Mardi Gras (Fat Tuesday), the last day of the Carnival season. The origin of the name "carnival" is disputed. One theory states that the word comes from the Late Latin expression carne vale, which means "farewell to meat", signifying that those were the last days when one could eat meat before the fasting of Lent. Other sources, however, suggest that the name comes from the Italian carne levare or similar, meaning "to remove meat", since meat is prohibited during Lent. According to the Oxford English Dictionary, the word "Carnival" is derived from Latin carnem levare (removal of the meat) or carnem laxare (leaving the meat).
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