In Biblical times, ashes were used to express grief or sorrow for sins and faults. Several of the prophets in the Old Testament call on Israel to repent and use the image of ashes and sackcloth to emphasize this repentance. Ashes were also used to prepare for battle as seen in the Book of Maccabees. Christians continued to use sackcloth and ashes as a public sign of repentance into the Middle Ages. As Lent is a season of repentance, by the end of the 10th century, it was customary in Western Europe to receive ashes on the first day of Lent. This practice was extended to the entire Roman Church by Pope Urban II.
In the Latin Church, Ash Wednesday is observed as a day of fasting, abstinence from meat and repentance. Fasting rules require Catholics ages 18 to 59 to only consume one full meal and two smaller meals which combined do not equal a full meal. Abstinence rules forbid Catholics from eating meat, defined as coming from mammals and fowl.
During the medieval period, the day before Ash Wednesday was the required annual day of confessing one’s sins. The individual would receive absolution and the penances they were to perform during Lent. This is why the day before Ash Wednesday is sometimes referred to as Shrove Tuesday, from the term “shrove” meaning an “imposition of a penance.”
Not all Catholics observe Ash Wednesday. Eastern Rite Catholics, who do not count Holy Week as part of Lent, observe Clean Monday instead on the Monday before Ash Wednesday. This begins Clean Week in which Eastern Catholics are called to go to confession and clean their entire house in preparation for the coming season of Lent. Only the Maronite and Syro-Malabar Catholics Churches distribute ashes on Clean Monday. Similarly, Ambrosian Rite Catholics observe the beginning of Lent on the First Sunday of Lent and, thus, distribute ashes on that day.