They're in your stomach, your bloodstream, up your nose. They're all over your body and they're one of hottest topics in scientific research now. The trillions of microbes and bacteria that live on, and in and around us, go by the name of the microbiome – and each of us carries our own individual boutique blend of bacteria -- as traceable as fingerprints. Scientists are just now beginning to understand how they affect our immune system, and the role they play in such diseases as diabetes, obesity, Crohn's disease and allergies. Meanwhile, a multi-billion-dollar probiotics industry has built its empire on the research into the microbiome, and promises to correct our faulty gut bacteria and restore our health. Is there truth in the hype? What do we really know about our individual microbial signatures? We separate the facts from the fads.