This week is known in some Christian denominations as "Holy Week."
It marks the events leading up to and including the arrest, crucifixion, death and resurrection of Jesus Christ.
Here is more about the individual days of Holy Week.
Also, here is an explanation of some of the different services a person may encounter throughout the week.
Holy Week begins with Palm Sunday, the commemoration of Jesus' final entrance into Jerusalem.
Some churches distribute palm fronds to their congregations.
The Monday and Tuesday of Holy Week are known as "Holy Monday" and "Holy Tuesday," but in Western Christianity, these days do not have widespread particular traditions or liturgy associated with them.
The Orthodox churches, however, observe "Service of the Bridegroom" from the evening of Palm Sunday until the end of Holy Tuesday, says the Greek Orthodox Archdiocese of America website.
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Churches in Orthodox Christianity follow the Julian calendar to determine the date of certain holidays, including Easter.
This is why Orthodox Easter is typically about a week after Easter is celebrated, according to History.com.
The Wednesday of Holy Week is known as both "Holy Wednesday" and "Spy Wednesday," as this was the day that Judas made arrangements to betray Jesus, according to National Catholic Register.
Today, many churches typically offer a Tenebrae service on Spy Wednesday.
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Tenebrae, which means "darkness" or "shadows," is a service that focuses on the Passion of Jesus Christ. It's the week of the crucifixion and resurrection of Christ, as Christianity.com notes.
Tenebrae dates back to medieval times.
"The service includes a series of Scripture readings commemorating Jesus’ final week, ending with his burial," notes the Diocese of Portland in Maine.
At the conclusion of each reading, a candle is snuffed out, until the final candle, the Christ candle, is carried out.
That leaves the room in darkness and allows for participants to reflect on the "great emotional and physical pain that was very real for Jesus during his Passion," the site also notes.
The Paschal Triduum, also known as the "Easter Triduum," is the shortest liturgical season of the year, lasting just three days.
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The word "Triduum" refers to a three-day observance.
The Triduum is observed in a variety of liturgical traditions, including some Protestant denominations.
It begins on Holy (Maundy) Thursday with the evening Mass of the Lord's Supper, and concludes at evening prayer on Easter Sunday, notes the United States Conference of Catholic Bishops (USCCB).
"Though chronologically three days, they are liturgically one day unfolding for us the unity of Christ's Paschal Mystery," says the USCCB.
During the Triduum, the Catholic Church ceases using bells during Mass and the Gloria is not sung after Holy Thursday until Holy Saturday.
Instead of bells, some churches opt to use a wooden clacker, or "crotalus." It's an instrument similar to a rattle, notes the website for St. Patrick's Guild, a religious supply retailer.
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"The sweet rings of altar bells are not appropriate after the Gloria on Holy Thursday through the Gloria on Holy Saturday," the site indicates.
"Therefore rare instruments, like wooden clackers, are used to maintain an appropriate somber mood where the altar bells would be rung," the site also notes.
"The clacker is sounded at the consecration of the gifts during the liturgy of the Eucharist, reminding the congregation of the awesome transformation that takes place at these moments," it also notes.
Holy Thursday is the first day of the Paschal Triduum and commemorates the Last Supper.
It is also known as "Maundy Thursday" in some traditions.
Christians believe that at the Last Supper, Jesus Christ instituted the New Covenant and celebrated the first Eucharist.
In some churches, priests may opt to wash the feet of a select group of congregants in imitation of Christ during the Last Supper, but this is optional, says the USCCB's website.
Mass on Holy Thursday marks the official start of the Triduum.
Good Friday is the day Christians believe that Jesus Christ was sentenced to death and crucified.
It is called "Good Friday" in English, as the term "good" is synonymous with "holy," notes Dictionary.com.
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Good Friday is traditionally a day of fasting and abstinence from meat, notes the USCCB.
In the Catholic Church, no sacraments are to be celebrated on Good Friday, except for confession and the anointing of the sick.
Mass is not celebrated on Good Friday; rather, a "service" using pre-sanctified communion is often held, says the USCCB website.
Those who attend the Good Friday service are given the opportunity to venerate a cross and to further reflect on Jesus' death.
The Stations of the Cross are prayed traditionally on Fridays during Lent, including Good Friday, notes Encyclopedia Britannica.
The Stations of the Cross is a devotional prayer centered on 14 (eight in some Protestant traditions) events that occurred on the day Jesus was sentenced to death, crucified and subsequently died, says the website Joyful Heart Renewal Ministries.
The devotion dates back in some form to the 13th century and "involves meditating at way stations on the way to the Cross, recalling Jesus' journey along the Via Dolorosa in Jerusalem on Good Friday," the site also notes.
Holy Saturday, the day before Easter, is the day that Jesus — his body in the tomb — descended into hell for the harrowing of hell.
In Orthodox tradition, "On Great and Holy Saturday the Church contemplates the mystery of the Lord's descent into Hades, the place of the dead," says the Greek Orthodox Archdiocese of America website.
"On Great Saturday our focus is on the Tomb of Christ. This is no ordinary grave. It is not a place of corruption, decay and defeat. It is life-giving, a source of power, victory and liberation," that website also notes.
That evening, Holy Week shifts dramatically as the focus is now on the imminent resurrection of Christ.
The Easter Vigil is celebrated by some churches the day before Easter, after sundown.
"The Easter Vigil marks the end of the emptiness of Holy Saturday, and leads into the celebration of Christ’s resurrection," says the website for the Church of England.
Catholic, Anglican and some Lutheran churches include the "Exsultet," an "ancient hymn of triumph and rejoicing," says the Church of England.
The singing of the Exsultet "links this night of our Christian redemption to the Passover night of Israel’s redemption out of Egypt," they note.
Unlike in a typical Sunday Mass, which includes three Bible readings, the Easter Vigil Mass is considerably longer.
"One of the unique aspects of the Easter Vigil is the recounting of the outstanding deeds of the history of salvation," says the USCCB website.
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"These deeds are related in seven readings from the Old Testament chosen from the law and the prophets and two readings from the New Testament, namely from the Apostle Paul and from the Gospel," the site continues.
In the Catholic Church, the Easter Vigil is traditionally when those entering the Church are baptized, confirmed and receive their first Eucharist.
Easter Sunday is a day celebrating the resurrection of Jesus Christ in his victory over the grave.
It is the holiest day of the year in all of Christianity, notes Catholicaction.org.
Christians believe that Jesus Christ rose from the dead and acted as the sacrificial lamb to repay the debt of the sins of all humanity.
In the Catholic Church, the faithful are given the opportunity to renew their baptismal promises on Easter Sunday.
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"Mass is to be celebrated on Easter Day with great solemnity," says the USCCB website.
"A full complement of ministers and the use of liturgical music should be evident in all celebrations."
Outside a church context, Easter is typically celebrated with symbols of rebirth, including eggs and baby animals, as well as sweet products such as chocolates and candies.
The tradition of exchanging Easter baskets dates to the 12th century Poland, says the website Catholic Witness, and traditionally involved food that was not eaten during Lent.
