Grid Structure, Stability, and Balance opens with an experience of the author to instill electric grid operators’ concern with ever-present threats of a widespread blackout. The narrative proceeds to explain what needs to be known about the generation, transmission, and distribution of electricity to understand the changes that will come with decarbonized power production. Emphasized are the structure and geographic distribution of synchronous grids, the rotational inertia of turbines essential in maintaining grid stability, and the balancing requirement that supply must exactly balance demand, always and everywhere.