In chemical reactions, a catalyst serves as a substance that accelerates the rate of the reaction by providing an alternative pathway with lower activation energy. In this section, we highlight the mechanisms by which a catalyst works and clarify that it affects the rates of both the forward and reverse reactions equally, thereby not influencing the overall equilibrium position. Using the example of ammonia synthesis, we explain how Fritz Haber’s introduction of iron catalysts enabled industrial processes to operate efficiently at temperatures where overall yields would otherwise be unfavorable. The section emphasizes that while catalysts can enhance the speed of reactions to reach equilibrium, they do not affect the equilibrium constant or the proportions of reactants and products at equilibrium.