There is, perhaps, no office in the whole liturgy so peculiar, so interesting, so composite, so dramatic as the office and ceremonial of Good Friday.

THE MORNING SERVICE

The service of this morning consists of four parts which we now proceed to explain. First of all, we have the lessons; next, the prayers; thirdly, the veneration of the cross; and lastly, the Mass of the Presanctified. These solemn and unusual rites announce to the faithful the sacredness of this day, as also the suspension of the holy Sacrifice, for which they are substituted. The altar is stripped; the cross is covered with a black veil; the candles are of yellow wax; everything in the sanctuary bespeaks mournfulness.

Holy Church is now going to relate to us the history of our Savior's Passion. It is St. John, the fourth of the evangelists, and an eyewitness of what took place on Calvary, who is about to describe to us the last moments of Jesus' mortal life. Let us be all attention, and beg our Lord to give us something of that devotion, which filled the soul of His beloved disciple as he stood at the foot of the cross.

ADORATION OF THE CROSS

The prayers are ended. The charity and zeal of the Church have embraced the whole universe of men, invoking upon them the merciful effusion of that precious Blood, which is now flowing from the Wounds of her crucified Lord. She turns next to her faithful children. Filled with holy indignation at the humiliations heaped upon her Jesus, she invites us to a solemn act of reparation: it is to consist in venerating that cross which our divine Lord has borne to the summit of Calvary, and to which He is to be fastened with nails.

But the Church is not satisfied with showing her children the cross that has saved them; she would have them approach, and kiss it. The priest leads the way. He has already taken off his chasuble; he now takes off his shoes also, and then advances towards the place where he has put the crucifix. He makes three genuflections at intervals, and finally kisses the cross. The deacon and subdeacon follow him, then the clergy, and lastly the people.

MASS OF THE PRESANCTIFIED

So vividly is the Church impressed with the remembrance of the great Sacrifice offered today on Calvary, that she refrains from renewing on her altars the immolation of the divine Victim: she contents herself with partaking of the sacred mystery by Communion. After the priest has resumed his chasuble, the clergy go in procession to the altar, where the consecrated Host has been reserved since yesterday's Mass. The deacon takes the chalice which contains it, and places it on the altar. The priest, having offered the homage of his adoration to our Redeemer, takes into his hands the chalice wherein He is inclosed whom heaven and earth cannot contain. The clergy, with lighted tapers in their hands, return to the high altar, and sing, during the procession, the hymn of the cross, Vexilla Regis Prodeunt.

TRE ORE

"Three hours" - referring to the three hours that Christ was on the Cross on Good Friday. While no definite ritual is prescribed, the customary Tre Ore service on Good Friday from noon to three is a series of sermons on the seven last words of Christ, along with appropriate hymns, periods for silent meditation, and the Stations of the Cross. (Catholic Dictionary)

—
Text taken from The Catholic Encyclopedia 1917 & The Liturgical Year