Photo credit: http://armyfamilyok.wordpress.com/2011/03/09/my-lent-calendar/
Cut and pasted from the BBC website:
Lent is the period of forty days which comes before Easter in the Christian calendar, traditionally a time of fasting and reflection. It is preceded by Shrove Tuesday and begins with Ash Wednesday.
Lent is the period of 40 days which comes before Easter in the Christian calendar. Beginning on Ash Wednesday (today), Lent is a season of reflection and preparation before the celebrations of Easter. By observing the 40 days of Lent, Christians replicate Jesus Christ's sacrifice and withdrawal into the desert for 40 days. Lent is marked by fasting, both from food and festivities.
Whereas Easter celebrates the resurrection of Jesus after his death on the cross, Lent recalls the events leading up to and including Jesus' crucifixion by Rome. This is believed to have taken place in Roman occupied Jerusalem.
The Christian churches that observe Lent in the 21st century (and not all do significantly) use it as a time for prayer and penance. Only a small number of people today fast for the whole of Lent, although some maintain the practice on Ash Wednesday and Good Friday. It is more common these days for believers to surrender a particular vice such as favourite foods or smoking. Whatever the sacrifice it is a reflection of Jesus' deprivation in the wilderness and a test of self-discipline.
Photo credit: http://www.conservapedia.com/Ash_Wednesday
Ash Wednesday is the beginning of Lent for Western Christian churches. It's a day of penitence to clean the soul before the Lent fast. Roman Catholic, Anglican, and some other churches hold special services at which worshippers are marked with ashes as a symbol of death and sorrow for sin.
In Ash Wednesday services churchgoers are marked on the forehead with a cross of ashes as a sign of penitence and mortality. The use of ashes, made by burning palm crosses from the previous Palm Sunday, is very symbolic.
More information here: