Microbes are often imagined as pathogens, drug-resistant superbugs, toxin-contaminated water supplies, and biofouling organisms. However, we now realize that there are many beneficial microbes that live in or on us, and it is these native ‘commensal’ microbes that drive much of what we think of as being human. Specifically, there are more microbial cells than human cells in our body (and 100 times more microbial genes!), and this collection of microbes – your microbiome – is increasingly being recognized to control our food cravings, obesity, behavior, aging, and susceptibility to disease. Beyond humans, microbes are now known to control the nutrient and energy cycles that run ocean and soil ecosystems and the planet at large. Though less studied, viruses also modulate these microbial impacts via killing, transferring niche-defining genes (e.g., antibiotic resistance), and reprogramming. This emergent field, Microbiome Science, is intensively interdisciplinary, leverages many OSU areas of excellence, and is already transforming the life sciences and our understanding of the rules of life.