Film noir is a style of Hollywood crime dramas that emphasizes cynical attitudes and motivations. The 1940s and 1950s are generally regarded as the "classic period" of American film noir. Film noir of this era is associated with a low-key, black-and-white visual style that has roots in German expressionist cinematography. Many of the prototypical stories and attitudes expressed in classic noir derive from the hardboiled school of crime fiction that emerged in the United States during the Great Depression, known as noir fiction.