In the Early Church everyone, clergy and laity alike, received Holy Communion in the same manner: receiving the consecrated Body of Christ (under the form of Bread) in their hands and then placing it in their own mouth, and sipping directly from the Chalice. In time, concern over the danger of crumbs being accidentally dropped on the floor or some of the consecrated Blood of Christ (under the form of Wine) being spilt, lead to the use of tongs, with which the elements were mingled together and placed carefully into the mouths of the communicants. By the ninth century, the Church began to use the Communion spoon for the same practical reasons, and it is this practice that remains in place today (though the clergy still receive in the ancient manner as they stand at the Holy Table).
In the Byzantine Rite, when it comes time for the Communion of the faithful, the Lamb (Host) is cut into smaller portions and placed in the Chalice, and thus distributed to the faithful using the Spoon. In this way, the faithful receive both the Body and the Blood of Christ, without taking the Mysteries into their hands. At the end of the Liturgy, the deacon will use the Spoon to consume the remaining Gifts (Body and Blood of Christ), and then ablute the Spoon, Spear and Chalice using wine and hot water (the Diskos is usually abluted only with hot water).
Since the Spoon is one of the Sacred Vessels it is usually kept on the Table of Oblation (Prothesis), where the bread and wine are prepared for the Eucharist. Often when a Chalice and Diskos (Paten) are made, an Asterisk, Spoon, and Spear will be made to match them. Because it touches the Body and Blood of Christ, the liturgical spoon should be made of gold, or at least be gold plated.
The Spoon is also used to prepare the Presanctified Gifts at the Sunday Liturgies during Great Lent, and the Reserved Mysteries on Great Thursday of Holy Week. The priest will take up the Lamb in his left hand and hold it over the Chalice. With the Spoon in his right hand, he will pour some of the Blood of Christ onto the underside of the Lamb, where the cross had been cut with the Spear during the Proskomedie.
The Spoon, being a sanctified object, may not be used for any purpose other than the liturgical uses for which it is appointed, and no one of lower rank than a deacon should touch it.