During Holy Week, which begins on Palm Sunday (March 20), Lent ends and the Easter triduum begins. The triduum is a single three-day celebration of the Paschal mystery. It opens with the Mass of the Lord’s Supper on Holy Thursday evening, has its center in the Easter Vigil and closes with Vespers — or Evening Prayer — on the Sunday of the Resurrection.

Here is a short explanation of what happens at your parish and at parishes all over the world, during this sacred time:

Holy Thursday, this year on March 24, commemorates the Last Supper when Jesus instituted the Eucharist and established the sacrament of ordination for the priesthood. Mass is always celebrated in the evening, and during that Mass, the chrism and holy oils, used for baptism, confirmation and the anointing of the sick, are brought forward. This Mass also includes the rite of the washing of the feet. The Eucharist is celebrated and following the prayer after Communion, the Blessed Sacrament is transferred to a place of reposition and the main altar is stripped bare.

Good Friday, March 25, is the most somber day of the church year. Many Catholics pray the Stations of the Cross, especially during the afternoon hours. It is a day of fasting and abstinence and it is unique in that it is the only day of the year when Mass is not celebrated. The solemn liturgy on Good Friday is known as the Celebration of the Lord’s Passion. The liturgical color is red, representing the suffering and death of Jesus. The readings are from the Book of the Prophet Isaiah and from the Letter to the Hebrews. The Gospel is John’s proclamation of Our Lord’s Passion. The second part of the liturgy is the veneration of the cross, followed by a Communion service.

Holy Saturday, March 26, is a solemn day of waiting, commemorating when Christ was in the tomb. The Easter Vigil takes place after night has fallen, beginning with a service of light. Some of the faithful gather around a fire to light the Easter candle. The priest is dressed in white vestments and lights the symbolic candle and the incense. Then he and other participants process to the church.

Saturday’s Liturgy of the Word contains between three and seven readings from the Old Testament, with the story of the Hebrews deliverance from slavery in Egypt always included. Each reading is followed by a psalm and prayer. The opening prayer for the Vigil is recited, followed by New Testament readings and the Gospel this year is from Luke. Following the readings, altar candles are lighted, illuminating the church that has been decorated in honor of the risen Lord.

The Easter Vigil is the time when most new Catholics are received into faith communities. Those who are being baptized are represented and assembled around the baptismal font, where they profess their faith and receive the sacrament. Following the baptism, the faithful renew their baptismal vows. The priest sprinkles the assembly with holy water and the newly received are confirmed. Then the Liturgy of the Eucharist begins.

Easter Day Mass, this year on March 27, is when the faithful celebrate the resurrection and triumph of the Lord. The readings are from the Acts of the Apostles, the Colossians and the Gospel from John, all focusing on the ministry of Jesus and his resurrection. After the homily, the faithful renew their baptismal promises.

On Easter Sunday the triduum is concluded liturgically with Evening Prayer in the late afternoon or early evening. This is the beginning of the Easter Season, which is the 50 days from Easter Sunday until Pentecost Sunday, May 15.