Since the first century Christianity has set aside the Friday before Easter as being a holy day of remembering the sacrifice that Jesus made through his death on the cross. Beginning in the fourth century it was referred to as Holy or Great Friday. In the sixth century the church at Rome officially dubbed the day Good Friday.
It is a day of grieving the death of Jesus and the evil that besets the world even still today. It is a good day to stop think, meditate and pray. Consider what you can do to carry on his mission and through personal sacrifice bring love to others.