A less-studied part of the human microbiome is the virome, the population of viruses that live associated with our bodies. Purification of virus-like particles from human intestinal contents yields around one billion particles per gram. Saliva contains around 100 million particle per ml. Most of these viruses probably infect cellular members of the microbiota (bacteria, archaea, and microeukaryotes). A minority infect human cells. In the Bushman laboratory, we have carried out extensive targeted studies of the virome, providing unique insights into colonization of infants, contributions to diseases, and ongoing mechanisms of evolution.