A reaction mechanism is an explanation of the sequence of elementary steps that occur when reactants transform into products during a chemical reaction. It details the transient species formed and the changes in chemical bonds at each stage, providing a path through the potential energy surface. By mapping this stepwise process, chemists can identify the intermediates, which are unstable species formed and consumed within the overall reaction. Analyzing the relative rates of these steps allows for the determination of the rate-determining step—the slowest step in the mechanism—which dictates the overall kinetics and reaction rate. Understanding the mechanism is crucial for predicting reaction feasibility, optimizing reaction conditions, and developing catalysts that provide alternative, lower-energy pathways.