A paten, or diskos, is a small plate, often made of, but not limited to silver or gold.  It is used to hold Eucharistic bread which may be consecrated during the Mass.  It is generally used during the liturgy itself, while, where applicable, the reserved sacrament is stored in the tabernacle in a ciborium.

In many Western liturgical denominations, 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, sometimes attached to a short pole or which has an integral handle, 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:

"Sacred vessels should be made from precious metal. If they are made from a metal less precious than gold, they should generally be gilded on the inside."

 

However, provisions for vessels made from non-precious metals are made as well, provided they are made from other solid materials which in the common estimation

in each region are considered precious or noble