A transition state is a temporary, unstable arrangement of atoms that occurs during a chemical reaction. It represents the highest energy point along the reaction pathway, where reactants are transformed into products. This state is crucial for understanding how reactions occur and is often depicted in energy diagrams. In the context of reaction kinetics, the transition state is essential for determining the rate of a reaction. The energy required to reach this state is known as the activation energy. Once the transition state is achieved, the reaction can proceed to form the final products, completing the transformation.