How does metal corrode?

How does metal corrode or the process of corrosion on the metal and how to prevent it?

Corrosion is a physical molecular change that occurs from a reaction to elements the metal comes in contact with. It increases the size of the molecule causing the surface to blister, crack and peel. All metals don't corrode the same way.

The most common form of corrosion is rust, found in metals with an iron content. Phosphoric acid will change rust to black iron. Look for a product in home supply stores called Naval Jelly. It's a jelly with phosphoric acid. Clean the rust off best you can with a wire brush and/or a grinder and apply a generous coating of the jelly. In about 30 minutes the rust will be gone.

Note that cleaning off the loose rust is critical because any of it the jelly doesn't contact won't make the change.