Holy Week is the most solemn and glorious week in Christianity, the pinnacle of the liturgical year. It’s more sacred than Christmas! This is because Holy Week commemorates the final week of Our Lord’s life, the very purpose for which Christmas happened.
Sundown on Holy Thursday to sundown on Easter Sunday is considered the most solemn part of the liturgical year. This three-day period is referred to as the Easter Triduum, also known as the Sacred Triduum, or Paschal Triduum.
Basically, the Sacred Triduum is one great festival recounting the last three days of Jesus’ life on earth, the events of his Passion and Resurrection, when the Lamb of God laid down his life in atonement for our sins.
The evening Mass on Holy Thursday is referred to as The Mass of the Lord’s Supper. This is where the Church re-lives the institution of the Eucharist and the Holy Sacrifice of the Mass at the Last Supper, as well as the institution of the priesthood, which took place the evening before Jesus was crucified.
The Mass of the Lord’s Supper on Holy Thursday concludes with a procession of the Blessed Sacrament to the “altar of repose,” a place where the consecrated Host is kept, away from the main altar where Mass is normally celebrated.
Good Friday is a mandatory day of fasting and abstinence. This is the day of the crucifixion, the day Jesus died for the sins of the world.
Good Friday is the only day of the year on which no Masses are offered. These Good Friday services often take place at 3:00pm., the hour that Jesus
breathed his last on the cross
On this day Christ is in the tomb.
There is no daytime Mass on Holy Saturday. It is still a day of fasting and sorrow before the Easter Vigil begins that evening. We recall, with Mary and the disciples, that Jesus died and was separated from them for the first time as He lay in the tomb.
EASTER VIGIL / EASTER SUNDAY
A vigil Mass is held after nightfall on Holy Saturday, or before dawn on Easter Sunday, in celebration of the resurrection of Jesus. This is called the Easter Vigil: the most glorious, beautiful, and dramatic liturgy for the Church.
Easter Sunday is what we’ve all been waiting for! The forty days of prayer, fasting, and almsgiving during Lent was in preparation for this day, when our hearts and souls can drink in deeply the culmination of the Paschal mystery: the Resurrection.
extract from https://www.catholiccompany.com/magazine/