This paper summarizes the field of static mixers including recent improvements and applications to industrial processes. The most commonly used static mixers are described and compared. Their respective advantages and limitations are emphasized. Efficiencies of static mixers are compared based both on theory and experimental results from the literature. The operations, which can benefit from the use of static mixers, are explored, namely, mixing of miscible fluids, liquid-liquid and gas-liquid interface generation, liquid-solid dispersion and heat transfer. Design parameters governing the performance of the various mixers in these applications are reported. The key parameters needed for the selection of a suitable mixer are highlighted.