This thematic issue demonstrates the development of flow chemistry from a prerogative of the petrochemical industry to a technology of enormous value for chemical synthesis and a key for sustainable manufacturing. Transformations viewed impracticable under batch conditions can be enabled by the precise reaction control of flow reactors: photochemical applications, handling of reactive intermediates or reactive reagents, and new heating concepts now allow for accelerated synthesis while only a small volume of the reaction mixture inside the flow reactor is exposed to extreme conditions. Technological advances, including miniaturization and automation, have rendered continuous flow processes an enabling technology for organic synthesis.