A benediction (Latin: bene, well + dicere, to speak) is a short invocation for divine help, blessing and guidance, usually at the end of worship service.
From the earliest church, Christians adopted ceremonial benedictions into their liturgical worship, particularly at the end of a service. Such benedictions have been regularly practiced both in the Christian East and West. At the time of the Reformation, Protestants abandoned many of the benedictions of the Roman Catholic Church, including the Apostolic Benediction made by the Pope and his delegates, the "last blessing" of the dying, and virtually all benedictions of inanimate objects.
A common form of benediction in Roman Catholic, and liturgical Protestant churches is for the worship leader to raise his hands and recite the words of the biblical Priestly Blessing ().
Some Protestant churches have recently started to reincorporate the use of benedictions in the closing of their church services. Such benedictions may be taken from Scripture, written by a church member, or a combination of the two.
In the Orthodox Church, benedictions will occur at both the beginning and the end of each service, and there may be other benedictions during the course of the service. The final benediction (the dismissal) is the most important, and will often entail mention of the feast or saint being commemorated that day. The priest will bless with his right hand, and the bishop will bless with both hands. In both cases, the hand is held so that the fingers form the initials IC XC (the abbreviation for "Jesus Christ" in Greek), and he traces the Sign of the Cross in the air with his hand. If a bishop or abbot is holding his crozier while making the benediction, he will raise his right hand and trace the Sign of the Cross with both his crozier and right hand, crossing the one in front of the other. More solemn benedictions, such as that which comes at the end of the Divine Liturgy, will be made with a blessing cross rather than the hand.
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: http://www.newadvent.org/cathen/02465b.htm