Studies of the microbiome—the array of bacteria, fungi, viruses, and other microorganisms living in or on a given individual or environment—generate a lot of data. An investigation of the skin microbiome of people with eczema, for example, would include not only the identities of the microbes present, but also a vast amount of metadata, or data about the data, such as the sex, age, weight, and disease status of the individuals under study. Analysis tools that integrate metadata have the potential to reveal connections between the microbiome and clinical outcomes.