In practice the director will delegate many of these responsibilities to other members of his film crew. For example, the director may describe the mood he or she wants from a scene, then leave it to other members of the film crew to find a suitable location, or to set up the appropriate lighting.
The degree of control that a director exerts over a film varies greatly. Many directors are essentially subordinate to the studio.
Other directors bring a particular artistic vision to the pictures they make (see auteur theory). Their methods range from some who like to outline a general plot line and let the actors improvise dialogue (such as Robert Altman and Christopher Guest), to those who control every aspect, and demand that the actors and crew follow instructions precisely (such as Alfred Hitchcock and Stanley Kubrick). Some directors write their own scripts.
Directors often work closely with film producers, who are responsible for the non-artistic elements of the film, such as financing, contract negotiation and marketing. Directors will often take on some of the responsibilities of the producer for their films (e.g. Steven Spielberg), or work so closely with the producer that the distinction in their roles becomes blurred (as is the case with Joel and Ethan Coen).