It is commonly written that Sir Humphrey Davy was the first investigator of the practice of preferential corrosion of metals, but there is evidence that the Romans (Baeckmann, 2009) got there first and protected their copper fastenings with lead caps on their marine craft. Of course Davy was important, but it was Robert Kuhn who can be considered the father of impressed current cathodic protection (ICCP) as shown in Figure 2.1, while also developing, by trial and error, in 1928 a protection criterion of −850 mV with respect to a copper/copper sulphate electrode which is still in widespread use today. After the second world war, the use of cathodic protection (CP) became widespread in both the United States and Northern Europe on pipelines, tanks and other ferrous objects, first mainly with galvanic anodes, but as time progressed, more commonly with impressed current systems. The present situation is that all commercial shipping, gas pipelines and oil lines are universally protected, and there is CP 18routinely used on a whole host of other products such as water heaters, outboard engines and storage tanks.