HotMedia is a novel scalable solution for delivering interactive rich media over the Internet. It is a delivery-suitable file format that can contain heterogeneous compositions of media bit streams as well as meta-data that define the behavior, composition, and interaction semantics. This enables the creation of lightweight single-file representations of interactive, multiphase presentations involving multiple media-type content. The HotMedia client has a smart content algorithm that infers types from the incoming data stream and fetches the media renderer components, user-interface components, and hyper-linked action components, all just-in-time, resulting in progressive and contest driven enrichment of the user experience. Internet users get a simple initial experience with minimal latency followed by enrichment of this experience. HotMedia has an open and extensible architecture, which enables and encourages the inclusion of new media-types, user-interfaces, and hyper-linked actions. By separating media-rendering from action-performing, it lets all media handle the same actions. HotMedia can also track on the server-side, user interactions and user-experience associated parameters. In its simplest usage HotMedia requires no more than a regular web server for delivery and no client-side preinstallation.