Droplet-based microfluidic systems allow the generation and manipulation of discrete droplets contained within an immiscible carrier fluid. Such systems leverage immiscibility to create discrete fL-nL volumes that reside and move within a continuous flow. Monodisperse droplets can be generated at rates in excess of tens of KHz, with independent control over each droplet in terms of its size, position and chemical payload. Significantly, the use of droplets in complex chemical and biological processing relies on the ability to perform a range of integrated, functional operations in high-throughput. Such operations include droplet generation, droplet merging/fusion, droplet sorting, droplet splitting, droplet dilution, droplet storage and droplet sampling. We have used a range of passive droplet-based microfluidic systems (i.e. those in which droplet operations are effected through the variation of channel/feature geometries) to perform a variety of experiments inaccessible to both macroscale and continuous flow formats. Applications include intelligent nanomaterial synthesis ☍, cell-based assays ☍, high-throughput screening ☍ and DNA amplification ☍. In all these areas, adoption of a droplet-based format transforms the efficiency of the reactive process or assay (through compartmentalization and confinement) and analytical throughput (due to the fact that tailored droplets may be produced at extremely high rates). It is significant to note that over the past decade, the development of droplet-based microfluidic technologies has occurred at a startling pace, with a focus on establishing functional operational components (for droplet processing) and pinpointing applications where the features of such systems may be used to the best effect. Based on their ability to perform complex experimental workflows in a rapid, efficient and robust fashion, the next decade will undoubtedly see the commercialization of many platforms for defined biological and chemical applications.