The first of the forty days of Lent, named for the custom of placing blessed ashes on the foreheads of worshipers at Ash Wednesday services. The ashes are a sign of penitence and a reminder of mortality, and may be imposed with the sign of the cross. Ash Wednesday is observed as a fast in the church year of the Episcopal Church. The Ash Wednesday service is one of the Proper Liturgies for Special Days in the BCP (p. 264). Imposition of ashes at the Ash Wednesday service is optional.
(from the Episcopal Church website)
Ash Wednesday derives its name from the placing of repentance ashes on the foreheads of participants to either the words “Repent, and believe in the Gospel” or the dictum “Remember that you are dust, and to dust you shall return.” The ashes may be prepared by burning palm leaves from the previous year’s Palm Sunday celebrations.
Because it is the first day of Lent, many Christians, on Ash Wednesday, often begin marking a Lenten calendar, praying a Lenten daily devotional, and abstaining from a luxury that they will not partake of until Easter Sunday arrives.