When a culture accepts something as an invention, that something has already attained the status of a fact that exists and can be questioned regarding its usefulness or function. But what happens before that? How does the invented gain reality? As in art, theater, literature, and music, as well as in science? And with what consequences? The contributions in this volume all deal with a moment or a specific model of invention. Starting from the respective media involved, an attempt is made to reconstruct these moments and models. To learn something about the corresponding inventions, they are understood as results or effects of improvisation processes: improvisations in the sense that they are based on a fundamentally open scope for the future.