Everything of importance seemed to take place in church during medieval times, things like marriage or baptism or funerals. The church was the center of life in a medieval village and each church wanted to be unique and important. Thus we get Holy Relics.
A holy relic was something that had once belonged to or been touched by Jesus or one of the important Saints. The holy relic might be a bone fragment, a nail from the cross or even a piece of wood from the cross of Jesus. While most relics were probably fake, people believed in them and believed that they could work miracles. Larger churches might have several relics and the churches traded them and bought and sold them.