Distinctively, they are cynical, tarnished, obsessive (sexual or otherwise), brooding, menacing, sinister, sardonic, disillusioned, frightened and insecure loners (usually men), struggling to survive and ultimately losing. .
The females in film noir are either of two types - dutiful, reliable, trustworthy and loving women; or femme fatales - mysterious, duplicitous, double-crossing, gorgeous, unloving, predatory, tough-sweet, unreliable, irresponsible, manipulative and desperate women. Usually, the male protagonist in film noir has to inevitably choose (or have the fateful choice made for him) between the women - and invariably he picks the femme fatale who destructively goads him into committing murder or some other crime of passion. .
Film noir films (mostly shot in gloomy grays, blacks and whites) show the dark and inhumane side of human nature with cynicism and doomed love, and they emphasize the brutal, unhealthy, seamy, shadowy, dark and sadistic sides of the human experience. An oppressive atmosphere of menace, pessimism, anxiety, suspicion that anything can go wrong, dingy realism, futility, fatalism, defeat and entrapment are stylized characteristics of film noir. The protagonists in film noir are normally driven by their past or by human weakness to repeat former mistakes. .
Film noir is marked by expressionistic lighting, disorienting visual schemes and skewed camera angles, circling cigarette smoke, existential sensibilities, and unbalanced compositions. Settings are often interiors with low-key lighting, venetian-blinded windows, and dark and gloomy appearances. Exteriors are often urban night scenes with deep shadows, wet asphalt, rain-slicked or mean streets, flashing neon lights, and low key lighting. Story locations are often in murky and dark streets, dimly-lit apartments and hotel rooms of big cities. [Often-times, war-time scarcities were the reason for the reduced budgets and shadowy, stark sets of B-pictures and film noirs.