Lent is a period of penance and abstinence observed by many Christians. Lent usually begins on Ash Wednesday (itself a different date every year) and ends on Holy Thursday (the day before Good Friday when Christians commemorate Jesus Christ’s crucifixion). That’s a period of 40 days if you don’t count Sundays. Lent is an homage to Jesus’s 40 days spent fasting in the desert in preparation for his ministry on Earth.
The purpose of observing Lent is for Christians to prepare for the coming of Easter by getting closer to God and repenting of sins. So, the point of giving up something (i.e. fasting) is to do penance (a common practice used in many churches by which parishioners seek forgiveness), as well as to participate in some small way with Jesus’ suffering in the desert.
Often, people elect to give up something they really enjoy or depend on, like cigarettes, alcohol, fast food or chocolate. Others choose to fast from practices that don’t necessarily make them a better person, like gossiping or criticizing others.
Whatever you give up, intent is a big part of truly recognizing Lent. Jesus calls us to fast, but simply tells us to do it for the right reasons. It should not be for our glory, but for God’s. If we are doing something which is sinful then it would be good to try to stop doing it … But something which is not sinful can be given up, not because it is unclean but because we are called to something greater.”
extract from www.people.howstuffworks.com