Benediction of the Blessed Sacrament is a devotional ceremony celebrated within the Latin Rite of the Roman Catholic Church, as well as in some Anglican Churches, Western Rite Orthodox churches, and Latinised Eastern Catholic Churches.
Benediction of the Blessed Sacrament begins with the Exposition of the Blessed Sacrament (i.e., consecrated Host) in a monstrance set upon the altar. The liturgy includes singing the ancient Latin hymns written by St Thomas Aquinas, O Salutaris Hostia and Tantum Ergo, followed by the benediction proper. The celebrant holds the monstrance wearing a humeral veil covering his shoulders, arms and hands, and then blesses the faithful with the Blessed Sacrament by tracing the sign of the cross with the monstrance held steadily upright before him. The liturgy concludes with the Divine Praises and Psalm 117 with the antiphon, "Let us forever adore the Most Holy Sacrament."
The priest or deacon takes the consecrated host out of the tabernacle and places it in the monstrance (which has already been placed on the altar) while the faithful sing O Salutaris Hostia. The faithful kneel at the moment of exposition.
Adoration of the Blessed Sacrament is almost always done in silence. Where readings, songs, psalms, devotional prayers (such as the rosary, litany or a novena prayer) or a homily are incorporated, there are still usually lengthy periods of sacred silence for the faithful to be present to Christ in the Eucharist without distraction. Solemn Vespers or Evensong is often sung in the presence of the Blessed Sacrament.
Bringing adoration to a close and in preparation for the benediction while all kneel, the priest or deacon incenses the exposed host while the faithful sing the Tantum Ergo.
After the incensing the priest stands and dons the humeral veil, ascends to the altar and lifting the monstrance above his head traces a large cross.
After the benediction the priest removes the humeral veil and, while kneeling before the Blessed Sacrament, leads the faithful in the recitation or chanting of the Divine Praises.
Psalm 117 is sung with the antiphon "Let us adore forever the most holy sacrament" while the priest returns the Blessed Sacrament to the tabernacle.
The Blessed Sacrament is also adored by Roman Catholics and Anglo-Catholics outside of any liturgical rite. Some have cited reference to St. Basil in the fourth century , but Franciscan archives credit Saint Francis of Assisi (who died in 1226) for starting this devotion in Italy. The lay practice of adoration in France formally began in Avignon in September 1226. The adoration may also be nightly; e.g., the Venerable Leo Dupont initiated nightly adoration of the Blessed Sacrament in Tours in 1849, whence it spread within France. There are religious orders of monks and nuns committed to perpetual adoration of the Blessed Sacrament; some of their number (on a roster) always present in the chapel before the exposed Host.
The adoration of the Blessed Sacrament outside of Mass (extra-eucharistic devotion) is attested in numerous Catholic writings and inspirations; e.g., significant portions of the writings of the Venerable Concepcion Cabrera de Armida are reportedly based on her adorations of the Blessed Sacrament. Cabrera de Armida did not represent her writings as interior locutions or visions of Jesus and Mary but as her meditations and inspirations during Eucharistic adoration.
Also, at the Liturgy of the Presanctified Gifts, during the Great Entrance, as the priest carries the chalice and diskos (paten) to the Holy Doors, everyone prostrates themselves in veneration before the consecrated Gifts.