Palm Sunday, officially known as Passion Sunday, is celebrated by Christian communities on the Sunday before Easter.
It commemorates Jesus Christ's triumphal entry into Jerusalem, where he would be crucified days later.
Christ's procession into the city is described in the Bible, in the Gospels of Matthew, Mark, Luke, and John.
The Gospel writers chronicle how Christ rode into Jerusalem on a donkey while crowds placed palm leaves on the road before him and welcomed him into Jerusalem as their king.
The first evidence of special Palm Sunday ceremonies dates to the 4th century in Jerusalem.
The travelogue Peregrinatio Etheriae, or The Pilgrimage of Etheria, contains a personal written account of Christian pilgrims reenacting Christ's entry into Jerusalem.
The Bobbio Sacramentary, dated to the 8th century, provides the earliest evidence of ceremonies in the West, including the practice of blessing palm leaves that continues today.
Palms are blessed after the priest says a special prayer over them and sprinkles them with holy water during the Palm Sunday ceremony.
By the Middle Ages, complex processional ceremonies were standard fare.
They often involved starting a procession in one church, blessing palms in another, and returning to the first church to continue the procession with the blessed palms.
