Corrosion is the destructive attack of a material by reaction with its environment. The serious consequences of the corrosion process have become a problem of worldwide significance. In addition to our everyday encounters with this form of degradation, corrosion causes plant shutdowns, waste of valuable resources, loss or contamination of product, reduction in efficiency, costly maintenance, and expensive overdesign. It can also jeopardize safety and inhibit technological progress. The World Corrosion Organization estimates the global cost of corrosion to be roughly US$ 2.2 trillion annually, and that a large portion of this - as much as 25% - could be eliminated by applying simple, well-understood prevention techniques.