Ash Wednesday is the first day of Lent. The holiday derives its name from the ashes used to mark crosses upon the foreheads of the faithful observers.
Lenten Fast
Ash Wednesday marks the beginning of the Lenten fast. Lent practices vary among different Christian cultures, but generally include a partial fast or denial of food and drink. The fast is coupled with a period of pious self-examination, and ends on the Saturday after Good Friday. It is also customary for observers to give up something they indulge in, for example smoking, sweets or even texting.UCSM: Lent, Holy Week and Easter
The following churches are said to practice Ash Wednesday: Lutheran, Methodist, Presbyterian, Anglican and Roman and Eastern Orthodox Catholics.About.com: What Is Ash Wednesday