As a teacher of physical chemistry, I noticed that students, even in advanced classes, have difficulties in understanding the basics of redox chemistry. The quantification of redox quantities, such as potentials requires reference systems (or electrodes) for comparison. Section 4 discusses the importance of reference systems (or electrodes) in the determination of electrochemical quantities. Several reference electrodes with their standard potentials are provided, and the trends of redox potentials across the periodic table are discussed. In addition to reference electrodes, the quantification of redox quantities requires electrochemical cells. Section 5 summarizes the basic components of electrochemical cells in terms of electrode and electrolyte, as well as the main mathematical quantities governing the redox reactions at equilibrium explained by the Nernst equation. To further clarify the discussed concepts, numerous questions and problems with detailed answers are provided. Most of these questions are formulated by students like you. I believe that these two Sections (4 and 5) would greatly help students with levels varying from high school to advanced university classes.