Research: Director

A Director works underneath the Producer in the chain of command on a film production, controlling the actors and crew. They have control of the creative and artistic elements of a production, often being involved in the original writing of the screenplay all the way through to post-production editing. How much a director is involved with a film is often down to the individual directors style, for example: Christopher Nolan and Steven Spielberg often write and produce their films as well as direct them, Clint Eastwood and Mel Gibson regularly appear as characters in their own films, whilst James Cameron and the Coen brothers have been known to take part in cinematography and editing.

"Unlike television where the writer is in charge, in the movie world, the Director is king. The director of a movie is the commander and chief of a set. What he or she says goes everything from the look of the overall picture to the action contained within. They literally direct the movements of the actors, the choices of the shots, the rewrites of the script and the final edits. The director works closely with all major departments to make sure the project has all the elements they need. From the Cinematographer to the Gaffer to the Editor, they all take their direction from the Director"
http://filmtvcareers.about.com/od/basics/p/CP_FilmDirector.htm