The Diocese of Phoenix encouraged the faithful to take the Triduum as an opportunity to reflect on Jesus' love and sacrifice.

“As we enter into the Sacred Triduum, the holiest three days of the year, we invite you to remember and reflect upon our Lord's love for you - - a love so deep and personal, that he gave his very life so that you might spend an eternity with the Father in heaven,” the diocese posted on Facebook.

The Triduum begins with the Last Supper on Holy Thursday, continues through Good Friday and Holy Saturday, and concludes in the evening of Easter Sunday, according to the U.S. Conference of Catholic Bishops (USCCB). The three holy days are taken collectively to be considered as one day liturgically.

Besides marking the start of the Triduum, Holy Thursday is when a couple of traditions were started.

Jesus instituted the Sacrament of the Eucharist during the Last Supper, offering his body and blood to his disciples in the form of bread and wine, the USCCB said. He also instituted the priesthood, entrusting to his apostles the legacy of the church.

During Holy Thursday Mass, the priest washes the feet of several participants, representing a reproduction of Jesus' show of humility when he washed the feet of his disciples, according to the USCCB.

On Easter Sunday, the faithful celebrate Jesus' Resurrection, three days after his crucifixion, according to Christianity.com. Jesus' Resurrection not only confirmed that he was the true son of God, but also granted eternal life in Heaven to those who believe in him. The Resurrection is the cornerstone of the Christian faith.