Skin is now composed of a human part and a microbial part which is the more variable part. Up to now a lot of information could be obtained at the diversity, richness and taxonomic levels of microbiotas. Clinical trials are able to show effects which are documented by these descriptive levels but few explanation of effects are clearly described. Either way, it becomes essential to understand the mechanisms of action and the interaction of the human part with the microbial part to be able to master the safety and efficacy on the skin of drugs and cosmetics. This is possible with omics techniques, which however have different capacities and performances to answer these questions. Furthermore, it is now clear with the science of the microbiome that interactions such as the skin-gut axis are of paramount importance, which means that any knowledge of the microbiota can be beneficial for the skin microbiota understanding. Gilbert Skorski, CEO of Phylogene, explains.