A story like Heroes or Lost might spread from television into comics, the web, computer or alternate reality games, toys and other commodities,
and so forth, picking up new consumers as it goes and allowing the most dedicated fans to drill deeper. The fans, in turn, may translate their interests in the franchise into concordances and wikipedia entries, fan fiction, vids, fan films, cosplay, game mods, and a range of other participatory practices that further extend the story world in new directions. Both the commercial and grassroots expansion of narrative universes contribute to a new mode of storytelling, one which is based on an encyclopedic expanse of information which gets put together differently by each individual consumer as well as processed collectively by social networks and online knowledge communities.
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Let me start with the following definition of transmedia storytelling as an operating principle: "Transmedia storytelling represents a process where integral elements of a fiction get dispersed systematically across multiple delivery channels for the purpose of creating a unified and coordinated entertainment experience. Ideally, each medium makes its own unique contribution to the unfolding of the story." Some of what I will say here will complicate this conception of a "unified and coordinated entertainment experience," as we factor in the unauthorized, grassroots expansion of the text by fans or consider the ways that franchises might value diversity over coherence in their exploration of fictional worlds.
A transmedia story represents the integration of entertainment experiences across a range
of different media platforms.