Improvisation is the practice of making and creating in the moment and in response to the stimulus of one's immediate environment and inner feelings. This can result in the invention of new thought patterns, new practices, new structures or symbols, and/or new ways to act. This invention cycle occurs most effectively when the practitioner has a thorough intuitive and technical understanding of the necessary skills and concerns within the improvised domain. Improvisation finds popular use in most any art form, including drama, dance, music and film. A keen advocate of improvisation in film is director Mike Leigh, who uses lengthy improvisations developed over a period of weeks to build characters and story lines for his films. Throughout the history of cinema, a great amount of iconic moments resulted from actors’ spontaneous emotions and mood driven practice, one great example of which is Marlon Brando’s performance of Kurtz in Francis Ford Coppola’s Apocalypse Now, which had famously been improvised over large extents.