  The ability to measure the transcriptomes of single cells has only been
feasible for a few years, and is becoming an extremely popular assay. While
many types of analysis and questions can be answered using single cell
RNA-sequencing, a central focus is the ability to survey the diversity of cell
types within a sample. Unbiased and reproducible cataloging of distinct cell
types requires large numbers of cells. Technological developments and protocol
improvements have fuelled a consistent exponential increase in the numbers of
cells studied in single cell RNA-seq analyses. In this perspective, we will
highlight the key technological developments which have enabled this growth in
data.
