The Drop-Seq protocol, originally developed by Macosko et al. in 2015, is a high throughput method that enables the sequencing of the from a large number of cells. The power of this technology resides in the fact that during sequencing, one can where the original information came on a cell to cell basis. This allows oneto make a gene expression map of the cell, or even to distinguish cell populations within a tissue. This method relies on droplet microfluidics and library preparation for Next Gen Sequencing (NGS): droplets allow for rapid and efficient compartmentalization using low reagent volumes and NGS allows for fast and high throughput analysis of single-cell gene expression.