An electrocyclic reaction is a type of organic reaction where a conjugated system undergoes a ring closure or ring opening in response to thermal or photochemical conditions. This process typically involves the formation or breaking of sigma bonds while maintaining the pi bond framework, resulting in cyclic compounds. These reactions are governed by the Woodward-Hoffmann rules, which predict the stereochemistry and feasibility of the reaction based on the electron configuration of the reacting system. Electrocyclic reactions are important in synthetic organic chemistry for constructing complex cyclic structures efficiently.