A scenario (from Italian, that which is pinned to the scenery) is a synthetic description of an event or series of actions and events. In the Commedia dell'arte it was an outline of entrances, exits, and action describing the plot of a play that was literally pinned to the back of the scenery. It is also known as canovaccio or "that which is pinned to the canvas" of which the scenery was constructed.
Surviving scenari 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 forms the basis of 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. Modern commedia troupes most often make use of a script with varying degrees of additional improvisation (see improvisational theater).
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. that can be expanded later in a fully developed libretto, or script. This sketch can be helpful in "pitching" the idea to a prospective producer, director, or composer.
A scenario is also an account or synopsis of a projected course of action, events or situations. Scenario development is used in policy planning, organizational development and, generally, when organizations wish to test strategies against uncertain future developments.
Scenarios are widely used by organizations of all types to understand different ways that future events might unfold. Scenario planning or scenario analysis is a complex business process related to futures studies.
Scenarios should not be used to forecast what will happen. According to the Forecasting Dictionary, a scenario is “a story about what happened in the future”. Vivid scenarios distort people’s perceptions of the likelihood of the events they describe. Scenarios can therefore be used to overcome resistance to unpopular forecasts. Gregory and Duran (2001) examine principles for the use of scenarios in gaining acceptance of forecasts.