This year, Palm Sunday, which is one of the most important days in the Christian calendar, falls on Sunday, April 13.

Palm Sunday is the Christian celebration held the Sunday before Easter that marks the beginning of Holy Week, which is the week of events that lead up to the commemoration of Jesus' death and resurrection, according to ShareFaith.com.

Palm Sunday commemorates Jesus' entry into Jerusalem to celebrate Passover. The gospels record the arrival of Jesus into Jersualem while riding a donkey, while his acolytes spread palm branches and cloaks on the street to honor him as their messiah.

In biblical times, kings and aristocrats arrived on donkeys, as the donkey was a symbol of peace. The laying of palm branches also indicated that a king or dignitary was arriving in triumph.

The first celebration of Palm Sunday began in the Jerusalem Church in the late fourth century. Early Palm Sunday celebrations involved the singing of prayers, hymns and sermons, while people walked to holy sites around the city.

At the final site, where Christians believe Jesus ascended into heaven, the clergy would read from the gospels about the entry of Jesus into Jerusalem. Children would carry palm and olive branches, and the people would walk through the city back to the church, where they would hold evening services.

Palm Sunday had spread by the fifth century. Then, by the seventh century, there were two new Palm Sunday traditions: the blessing of the palms and a morning procession. The holiday was adopted by the Western Church in the eigth century, which is when it recieved the name "Palm Sunday."

In the present day, Palm Sunday traditions are mostly the same as in ancient times, with a ceremony that begins with the blessing of the palms, then a procession that is followed by Mass. Afterwards, congregants take palms home and place them around their homes.

In some countries, palms are placed on the graves of departed loved ones, and in colder climates where there are no palm trees, yew, willow or sallow brances are used.

The palms are then blessed and burned at the end of the day. The ashes are kept for next year's Ash Wednesday, the holiday that marks the beginning of Lent.