Classical Hollywood Studio System

Classical Hollywood can partially attribute its success to the effectiveness of the studio system of production and market control. One aspect of the system that I find particularly important is the star system. Within the star system, stars were discovered by the studio, signed a contract committing them to that studio, and then the studio would use them to promote their products, including other stars of that studio. The star system also created a net of associations connecting stars to certain genres within the studios they were associated with. Contracted stars would develop consistent sets of character traits that defined what roles they played in the studio's films. If a star became associated with a  "gangster" set of character traits, then the studio decided to make such a film, that star would be the most likely candidate to fill that role for the film, and as the star's popularity rose, a studio would be more inclined to produce gangster films with that star. For example, Humphrey Bogart's status as a contracted star with a knack for gangster roles for Warner Brothers led to a spurt of criminal/gangster films during the 1930s and later to detective films in the 1940s as the genre changed. As Bogart moved from gangster films to detective films, his character traits were still very consistent, and the image of Bogart wearing a raincoat and fedora became iconic for Warner Brothers Studio. 

(picture from http://www.forumgarden.com/forums/films-cinema-forum/49194-humphrey-bogart.html)