In our everyday lives many things that we need and use are covered in a surface material. Why, you might ask, is there any need to do this? There are several reasons. Some of the most common examples that you will come across are tinned goods and jewelry. The reason for this is to protect the metal underneath the coating. It is coated to stop it from rusting and tarnishing. In the case of the canned goods it is also to stop the food going bad. Whilst Tin, or more likely aluminium in modern times, is a perfect metal for making scores of cans it can affect the quality of the food. Therefore a coating of Nickel is used to stop the rust and to protect the food from the tin/aluminum.
In terms of jewelry, solid gold and silver are extremely expensive. Therefore a cheaper, but no less beautiful and effective method is to electroplate a ring by submerging it in a liquid gold or silver solution. This process is the same for the tinned goods. However, there are many other ways that surface treatment companies apply the coating. Some of these involve ultra heat sprays where the product is sprayed with a superheated plastic or ceramic.
Nickel is the metal that is used the most in coating. The reason for this is it does not rust or stain. However it is particularly hard to mine. The largest are in Canada, Russia and Australia. It is generally found where there has been a meteorite strike from the long distant past.