Ash Wednesday, a day of fasting, is the first day of Lent in Western Christianity. It occurs 46 days (40 fasting days, if the 6 Sundays, which are not days of fast, are excluded) before Easter and can fall as early as 4 February or as late as 10 March. This year Ash Wednesday is February 10th.
According to the canonical gospels of Matthew, Mark and Luke, Jesus Christ spent 40 days fasting in the desert, where he endured temptation by Satan. Lent originated as a mirroring of this, fasting 40 days as preparation for Easter. Every Sunday was seen as a commemoration of the Sunday of Christ’s resurrection and so as a feast day on which fasting was inappropriate. Accordingly, Christians fasted from Monday to Saturday (6 days) during 6 weeks and from Wednesday to Saturday (4 days) in the preceding week, thus making up the number of 40 days.