1. A method comprising: receiving media content descriptions by an interactive television server, the receiving media content descriptions including receiving data that identifies advertisements; receiving historical viewing data associated with multiple viewers by the interactive television server; defining relationships among the media content descriptions based on a determination that the historical viewing data indicates that at least one of the multiple viewers has viewed both a first media content and a second media content, without accessing a demographic viewer profile; generating a plurality of metadata maps that include representations of the relationships that are defined, the plurality of metadata maps being of various sizes so that client devices with less available memory can receive smaller metadata maps and client devices with more available memory can receive larger metadata maps; and selecting an advertisement to be rendered based on the relationships that are defined and viewing history data associated with a viewer, wherein the selecting is not based on demographic data associated with the viewer.