Drop-seq is a technology that allows biologists to analyze genome-wide gene expression in thousands of individual cells in a single experiment. This work is described in Macosko et al., Cell, 2015. Following the original Macosko publication, drop-seq is a strategy for quickly profiling thousands of individual cells by separating them into nanoliter-sized aqueous droplets, associating a different barcode with each cell’s RNAs, and sequencing them all together. Drop-seq analyzes mRNA transcripts from thousands of individual cells simultaneously while remembering transcripts’ cell of origin.