In the commedia dell'arte, it was an outline of entrances, exits, and action describing the plot of a play, and was literally pinned to the back of the scenery.
Surviving scenarios from the Renaissance contain little other than character names, brief descriptions of action, and references to specific lazzi with no further explanation.
It is believed that a scenario formed the basis for a fully improvisational performance, though it is also likely that they were simple reminders of the plot for those members of the cast who were literate.
In the creation of an opera or ballet, a scenario is often developed initially to indicate how the original source, if any, is to be adapted and to summarize the aspects of character, staging, plot, etc.
In the filmmaking of the early 20th century, film scenarios (also called "treatments" or "synopses"[2]) were short written scripts to provide narrative coherence that had previously been improvised.