In the performing arts, a period piece is a work set in a particular era. This informal term covers all countries, all periods and all genres. It may be as long and general as the medieval era or as limited as one decade, the Roaring Twenties, for example. A genre is a division of a particular form of art according to criteria particular to that form. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... The 1920s were a decade sometimes referred to as the Jazz Age or the Roaring Twenties, usually applied to America. ...
The criminal, violent, misogynistic, hard-boiled, or greedy perspectives of anti-heroes in film noir were a metaphoric symptom of society's evils, with a strong undercurrent of moral conflict, purposelessness and sense of injustice.
Film noir films (mostly shot in gloomy grays, fls and whites) thematically showed the dark and inhumane side of human nature with cynicism and doomed love, and they emphasized the brutal, unhealthy, seamy, shadowy, dark and sadistic sides of the human experience.
Film noir films were marked visually by expressionistic lighting, deep-focus or depth of field camera work, disorienting visual schemes, jarring editing or juxtaposition of elements, ominous shadows, skewed camera angles (usually vertical or diagonal rather than horizontal), circling cigarette smoke, existential sensibilities, and unbalanced or moody compositions.