What Is Ash Wednesday?

All the Catholic people I know resemble this picture on Ash Wednesday....

So what is Ash Wednesday?

According to the trusty source Wikipedia----

Ash Wednesday, in the calendar of Western Christianity, is the first day of Lent and occurs 46 days before Easter. It is a moveable fast, falling on a different date each year because it is dependent on the date of Easter. It can occur as early as February 4 or as late as March 10.

According to the canonical gospels of Matthew, Mark and Luke, Jesus spent 40 days fasting in the desert before the beginning of his public ministry, during which he endured temptation by Satan.^[4][5] Ash Wednesday marks the beginning of this 40-day liturgical period of prayer and fasting.

Ash Wednesday derives its name from the practice of placing ashes on the foreheads of adherents as a sign of mourning and repentance to God. The ashes used are typically gathered after the palms from the previous year's Palm Sunday are burned.^[6]

This practice is common in much of Christendom, being celebrated by Catholics, Anglicans, Lutherans, Methodists, Presbyterians, and some Baptist denominations.