Copper, alone or in an alloyed form, has been used in cooking utensils almost since the dawn of history. Copper's uniform heat conductivity makes it a good material for top-of-range cooking because the heat is distributed evenly. This property also enables copper serving utensils to keep foods warm and palatable.
Copper cooking surfaces are usually lined with tin, nickel, or stainless steel for two reasons:

1. Copper will react to foods with a high acid content, which in some cases could be toxic.

2 . Cooked foods left directly in contact with uncoated copper may become discolored. While it is not necessarily injurious to health, the discoloration tends to detract from the food's eye appeal.

Tin or nickel linings are not very durable, and therefore should be recoated if these surfaces wear thru to the copper on the inside of the pan.

Another manufacturing process bonds or laminates copper to stainless steel or other metals. A core of solid copper sandwiched between two layers of stainless steel is another way copper is used to distribute heat uniformly.