Earlier chapters described different electrochemical techniques useful in the elucidation of various reaction mechanisms. Often the conclusions drawn about a sequence of heterogeneous electron transfer and homogeneous chemical reactions are the result of ingenious exercises in deductive reasoning based on interpretation of the electrochemical response of the system. As the editor noted in his introductory chapter, some interpretations tend to be presented with a certainty that belies the shakiness of arguments based largely on circumstantial evidence.