The second term is transmedia storytelling.

This one is a little trickier, so I’m going to quote communications professor and television scholar Henry Jenkins:

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.

That’s a mouthful. But the upshot is that a transmedia story uses different channels to deliver different parts of the story. In practice, that ends up looking like, well…18 movies, 10 television series, 5 short films, etc.

Transmedia storytelling might sound similar to a paratext, but there’s an important difference. A paratext (a trailer or a DVD commentary track) is typically about the story. Transmedia is a way of delivering part of the story.

Or, to borrow a more formal analysis from Jason Mittell’s fascinating book, Complex TV: The Poetics of Contemporary Television Storytelling, paratexts “function primarily to hype, promote, introduce, and discuss a text,” while transmedia storytelling uses multiple channels that “function as ongoing sites of narrative expansion.”