The paten is the small, shallow metal dish on which the host rests during Mass. In the early Church they used to be large holding the bread for the whole congregation but with the introduction of hosts similar to those that we use today the paten became smaller until by the middle ages it only held the priest’s host.
As with the chalice it is to be made of precious metal – usually gold. If it cannot be made of solid gold the upper surface is covered in gold.
As a sign of their ordination the new priest is often presented with their own chalice and paten which they keep throughout their lives. Sometimes the chalice and paten that a priest received at his ordination will be placed in his coffin after he dies.
Because the paten may contain crumbs of the consecrated host it important that you keep it flat and carry it carefully when you clear things away after Mass.