The basic principle of droplet microfluidics is easy to appreciate: highly monodisperse aqueous droplets are generated in an inert carrier oil in microfluidic channels on a chip, and each droplet functions as an independent microreactor. Hence, each droplet is the functional equivalent of a well (or tube), yet the volume of the droplet is roughly a thousand to a million times smaller. Such a massive reduction in reaction volume provides considerable savings in reagent cost when performing large numbers of reactions in parallel. Furthermore, unlike the conventional microtiter plates or valve-based microfluidics, droplets are intrinsically scalable: the number of reaction ‘wells’ is not limited by the physical dimensions of the chip but scales linearly with the emulsion volume. Different microfluidic modules can be employed to manipulate droplets in a sophisticated, yet highly controllable manner. Large numbers of droplets (>10^9) can be generated at astonishingly high rates (>20,000 droplets per second), their size precisely tuned, new reagents introduced into pre-formed droplets at defined time points, and droplets split and sorted, thereby opening new opportunities for the single-cell omics field. Many practical microfluidic techniques have been developed to profile and even selectively purify single cells; however, the demand for methods with better analytical performance and improved high-throughput capabilities remains very high. We are working to fulfill this demand by enabling higher throughput, reduced reagent costs, scalability, and single-molecule resolution across a diverse set of quantitative experiments in cell biology and biomedicine.