Reaction intermediates are temporary species formed during a chemical reaction. They exist for a short time and are not present in the final products. These intermediates can be atoms, ions, or molecules that help facilitate the transformation of reactants into products. Understanding these intermediates is crucial for chemists to predict reaction pathways and mechanisms. Common examples of reaction intermediates include carbocations, carbanions, and free radicals. Their stability and reactivity can significantly influence the rate and outcome of a reaction. By studying these intermediates, scientists can develop better catalysts and improve industrial processes in fields like organic chemistry and pharmaceuticals.