The word microbiome has become a catch term only in the past decade, but it refers to something as old as humanity itself: the diverse and unimaginably vast population of microorganisms that share our bodies. These microbiota compose an ecosystem whose constituent cells and genes actually outnumber our own, and without which we would be unable to carry out many functions necessary for life. Medicine has succeeded in mapping much of the gut microbiome, but only recently has advanced technology enabled researchers to identify and study the inhabitants of the human respiratory system and possibly use this information to diagnose and treat respiratory disease.