In the era of Single-Cell Biology or Cytomics (as termed in the early 2000th) it is aimed to characterize every individual cell of an organism. Not only that, but for the Cell Atlas (or Human Cytome) Project it is intended to also characterize each cell type in various physiological states (quiescence, activation, aging, death). This ambitious goal is only reachable by combining the virtues of different scientific and technological disciplines such as high-end microscopy and cytometry, single cell genomics and proteomics, and bioinformatics. In the present discovery phase it becomes clear that the more cellular parameters (surface or intracellular markers such as peptides, sugar residues, lipids, gene expression profiles etc.) can be measured per individual cells the more functionally distinct cell subsets are identified. So far it’s a great bonanza for discovery as it is not foreseeable how many distinct cell subtypes exist in an organism but for unraveling it needs new technologies for highly multiplexed single cell analysis. The ideal technology for unraveling subsets in heterogeneous cell populations based on the complex combination (barcode) of a multitude of markers is flow and image cytometry. This field amazingly evolved in the last years. Here I will give an overview on the recent developments in complex instrumentation, dyes for specifically tagging cell properties (fluorochromes, nanoparticles, rare earth elements) and new bioinformatics approaches to visualize and analyze high-dimensional data. I will also emphasize on how different approaches could be combined for enabling the highest level of multiplexing.