Scientists have improved their understanding of a new form of cell-cell communication that is based on extracellular RNA (exRNA). RNA, a molecule that was thought to only exist inside cells, now is known to also exist outside cells and participate in a cell-cell communication system that delivers messages throughout the body. To better understand this system, the National Institutes of Health Common Funds Extracellular RNA Communication Consortium, which includes researchers from Baylor College of Medicine, created the exRNA Atlas resource, the first detailed catalog of human exRNAs in bodily fluids. They also developed web-accessible computational tools other researchers can use to analyze exRNAs from their own data. The study, published in the journal Cell, contributes the first ‘map of the terrain’ that will enable scientists to study the potential roles exRNA plays in health and disease.