Pots and pans are made from many different types of materials. If you’re looking for a durable pan, cast-iron and carbon steel is the way to go, however, they are heavy and capable of rusting. Nonetheless, they conduct heat evenly and maintain high temperatures due to their density. The most popular material for pots and pans is probably aluminum because it is lightweight and conducts heat efficiently throughout. Also, aluminum alloys help prevent dents in pots and pans. On the other hand, aluminum reacts with acidic foods and can stain and erode. Stainless steel is durable and non-reactive to acids, but it does not conduct heat evenly. Copper pots that are lined with tin or stainless steel are durable and believed to be the best conductor of heat. However, they are heavy and more expensive than other materials. Some stainless steel pots and pans are made with a copper-ply or aluminum bottom core to ensure even heat distribution without the disadvantages of aluminum or the expense of copper.

Source: http://en.wikipedia.org