N.B: Given that our Sunday Benediction is part of the public worship of the Church, this is currently suspended since 5 November 2020 until future notice. Once the current lockdown 2 measures are lifted Sunday Benediction will be restored as per usual.
One of the most generally popular of Catholic services is Benediction of the Blessed Sacrament, known in France as Salut and in Germany as Segen. It is ordinarily an afternoon or evening devotion and consists in the singing of certain hymns, or litanies, or canticles, before the Blessed Sacrament, which is exposed upon the altar in a monstrance and is surrounded with lights.
At the conclusion of this service, the priest, his shoulders enveloped in a humeral veil, takes the monstrance into his hands and with it makes the sign of the cross in blessing (hence the name: Benediction) in silence over the kneeling congregation. Benediction is often employed as a conclusion to other services e,g. Vespers, Compline, the Stations of the Cross, etc, but it is also still more generally treated as a rite in itself.
There is a good deal of diversity of usage in different countries with regard to details, but some of the elements are constant. The use of incense and wax candles, which even in the poorest churches must not be less than ten in number, the singing of the “Tantum ergo” with its versicle and prayer, and the blessing given with the Blessed Sacrament are obligatory everywhere. In Rome the principle obtains that the only portion of the service which is to be regarded as strictly liturgical is the singing of the “Tantum ergo” and the giving of the Benediction which immediately follows. This idea is emphasized by the fact that in many Roman churches the celebrant, vested in cope and preceded by thurifier, acolytes, etc., only makes his entry into the sanctuary just before the “Tantum ergo” is begun. Previously to this the Blessed Sacrament is exposed, informally so to speak, by a priest in cotta and stole; and then choir and congregation are left to sing litanies and canticles, or to say prayers and devotions as the occasion may demand, the whole service being of a very popular character.
In English-speaking countries the service generally begins with the entry of the priest and his assistants in procession and with the singing of the “O Salutaris Hostia” as soon as the Blessed Sacrament is taken out of the tabernacle. Indeed, in England the singing of the “O Salutaris” is enjoined in the “Ritus servandus”, the code of procedure approved by a former synod of the Province of Westminster. On the other hand, the Litany of Our Lady, though usually printed after the “O Salutaris” and very generally sung at Benediction, is nowhere of obligation. It may be added that further solemnity is often given to the service by the presence of deacon and subdeacon in dalmatics. When the bishop of the diocese officiates he uses mitre and crosier in the procession to the altar, and makes the sign of the cross over the people three times in giving the benediction. On the other hand, a very informal sort of service is permitted, where the means for carrying out a more elaborate rite are not available. The priest, wearing cotta and stole, simply opens the tabernacle door. Prayers and devotions are said or sung, and then the priest blesses those present with the veiled ciborium before the tabernacle door is again closed. The permission, general or special, of the bishop of the diocese is necessary for services where Benediction is given with the monstrance.
Source: New Advent. Read the full article here http://www.newadvent.org/cathen/02465b.ht