Electrochemical technologies are an integral part of modern life. Because electrochemical reactions are coupled to electrical current, their rates are relatively easy to measure, control, and to exploit for work. Thus, methods based on electrochemical phenomena are ideal for sensors, energy storage and conversion, and microfabrication processes. Furthermore, the use of electricity for oxidation and reduction may allow clean production of chemicals. Concepts used to scale electrochemical systems are both similar to and different from those used for chemical systems. This text provides an introduction to the fundamentals that may allow understanding of existing electrochemical products and may inspire ideas for yet-to-be-invented products.