A paten, or diskos, is a small plate, usually made of silver or gold, used to hold Eucharistic bread which is to be consecrated. It is generally used during the service itself, while the reserved hosts are stored in the Tabernacle in a ciborium.
Within the Latin-Rite, the paten is typically either a simple saucer-like plate or a low bowl. A smaller style paten will often have a depression that allows it to securely sit on top of the chalice.
In more traditional denominations or parishes, altar servers may also use a small paten, usually attached to a short pole, which is placed under the chin of those receiving the Eucharist on the tongue; thus if the host accidentally falls, it would land on the paten rather than the floor.
The General Instruction of the Roman Missal lays down rules for patens: like the chalice, the paten "..should be made from solid materials which are considered suitable in each region. The conference of bishops will be the judge in this matter. Materials which do not break or deteriorate easily are to be given preference.. It is clear that patens and chalices do not have to be made of precious metal. Although this does not appear to rule out such a material as crystal, it would be considered unsuitable, whereas something such as ebony would be thought appropriate, and the use of a paten large enough for all is commended.
In the Eastern Orthodox and Greek-Catholic Churches, the Paten is called a diskos—also spelled (Church Slavonic: дискос; Greek: δισκάριον, diskarion) and is elevated by a stand (or "foot") permanently attached underneath. The diskos is usually more ornate than its Latin-Rite counterpart, and must always be made of gold or at least be gold-plated. The diskos may be engraved with an icon of Jesus Christ, the Nativity of Christ, a cross, or more frequently, an icon of the Theotokos.
When a diskos is made, it is usually accompanied by a matching asterisk (small, folding metal stand used to keep the Aër from disturbing the particles on the diskos), a spoon (for distributing Holy Communion to the faithful), and a spear (used to cut the Lamb during the Liturgy of Preparation).
For Christians of the East the diskos symbolises the Virgin Mary, who received Christ into her womb, and gave him birth; and also the Tomb of Christ which received his body after the Crucifixion, and from which he resurrected.
Sometimes, when a bishop celebrates the Liturgy, a smaller diskos is prepared for him with a small prosphoron from which he takes particles to commemorate the living and the departed before the Great Entrance.
When a priest is ordained, a portion of the Lamb will be placed on a small diskos and given to him, as a sign of the Sacred Mysteries which are being entrusted to his care.
Up until the first time a diskos is used in the Divine Liturgy it is considered to be an ordinary vessel, and may be touched by anyone. However, after having been used in the Divine Liturgy, a diskos may be touched only by a deacon, priest or bishop. A subdeacon may touch the sacred vessels, but only if they are securely wrapped in cloth.
When not in use, the chalice, diskos, and all the sacred vessels should remain on the Table of Oblation (prothesis), wrapped in their cloth bags—either sitting on top and covered with a cloth, or stored securely in a cabinet built into the prothesis.
In the usage of the Coptic Orthodox Church, the diskos usually has a flat bottom with no foot. Additionally, the it has a raised edge, forming a relatively high rim, preventing particles of the offered elements from falling to the floor.