This episode introduces chemical equilibrium, defining it as the point where the rate of the forward reaction equals the rate of the reverse reaction. This process is dynamic, meaning the reaction hasn't stopped, but the concentrations of all substances have become constant, though not necessarily equal. Equilibrium is indicated by a double arrow. The system's preference for either reactants or products is described as the equilibrium "lying to the left" or "lying to the right," respectively. The episode emphasizes the key misconception that equal rates imply equal concentrations, rather only the rates are equal, while the concentrations are constant.