It is a demonstration of mediaeval religious folklore held every night of 24 December in all the churches on the island of Majorca. Traditionally, a young person sings with at least two altar boys. They are accompanied by people of all generations to guarantee the custom is passed down. During the singing, the only musical support provided is the organ. This type of liturgical celebration used to take place in mediaeval Europe. Its preservation of tradition has earned it a place on the UNESCO Intangible Cultural Heritage of Humanity list.