Improvisation
Improvisation also refers to a type of performance.  Improvisation (or improv for short) is often used in comedy.  Actors or Improvisers will create an entire show that they make up as they go along. They will often ask the audience for an idea or suggestion. They will then do a short performance based on the suggestion. This lets them do many different short performances during each night's show. This is called "Short-form improv".