Film Noir 

Literally meaning 'black film'

The mood/atmosphere is often black and pessimistic, differing to typical glamorous Hollywood films at the time. It's visual aesthetic is very distinctive, featuring high contrast and it's stock characters include beautiful femme females and private detective (usually investigating corrupting police).

The term was first used in 1975 by Italian critic Neno Bruno and was influenced by Geraman Expressionism, first emerging in hollywood in early 1948 during the end of WW2 and the years shortly after. This type of film quickly gained much popularity due to the fat it could be cheaply made and had a very usual (for the time) pessimistic outlook on the world due to the brutality of the War.

Film Noir has a unique   visual style including:

•  Dark + Light
•  Shadows 
•  Silhouettes 
•  Blinds and Bars (to create a feeling of entrapment) 
•  Strange camera angles (Called Dutch angles, to create feeling of unease)
•  High contrast 
•  Black and white (reflecting the extremist/one-or-the-other views of film makers) 

It also includes such visual factors and techniques, many of which are still used today:

•  Rain 
•  Night 
•  Cityscapes 
•  Smoke/Cigarettes 
•  Urban areas/streets  
•  Cars 
•  Guns 

Film Noir illustrates such narrative elements:

•  Flashbacks
•  Voice over from the protagonist (to voice inner feelings go isolation)
•  Complicated and twisting plots + subplots 
•  Sudden reverses of fortune 
•  Circular narrative 
•  A network of minor characters 
•  Tragic endings