Palm Sunday Procession - Catholic Stock Photo

Palm Sunday is a Christian moveable feast that falls on the Sunday before Easter. The feast commemorates Christ's triumphal entry into Jerusalem, an event mentioned in each of the four canonical Gospels. It involves a ceremony known as the Blessing of the Palms that includes blessing palm fronds (or, in colder climates, replacements) with holy water outside the church (or, in cold climates, inside the narthex when Easter falls early in the year). The Palm procession, which follows the blessing of the palms, is a solemn gathering of the entire congregation. 

The focus of the Mass that follows the procession is Passion Sunday, which also falls on this feast day. The holy palms are regarded by the Catholic Church as sacramentals. The day's ceremonial attire is deep scarlet red, the color of blood, signifying Christ's ultimate atoning sacrifice.