In Western Christianity, Lent is the period from Ash Wednesday to Holy Saturday, the day before Easter Sunday.
Easter always falls on a Sunday between March 22 and April 25, roughly corresponding to the Northern Hemisphere's early spring. Ash Wednesday, which can fall anywhere between February 4 and March 10, occurs forty-six days before Easter, but Lent is nevertheless considered forty days long, because Sundays in this period are not counted among the days of Lent. The traditional reason for this is that fasting was considered inappropriate on Sunday, the day commemorating the Resurrection of Jesus.
Formerly Lent was referred to by the Latin term quadragesima, or the "fortieth day" before Easter. The name "Lent" comes from the Germanic root for spring (specifically Old English lencten). Initially the word simply meant spring, but later became associated with the fast. The name change occurred in the late Middle Ages as Catholic sermons were spoken in vernacular instead of Latin. As such, use of this term to describe this period is unique to English.
Easter celebrates the Resurrection of Jesus Christ, while Lent is a time of preparation for Holy Week. Holy Week recalls the events preceding and during the crucifixion, which occurred in Jerusalem in the Roman province Judea, AD 29. 
Purple, the color of royalty, repentance, and self-discipline, is the traditional color for the season of Lent.  Black, the somber color of mourning and sorrow for sin, is reserved for Good Friday and Ash Wednesday.