Understanding Genre

Genre is how you can identify a piece of media for example: books, movies or music. The genre is classified by a set of stylistic criteria.

Genre is the term for any category of literature or other forms of art or entertainment, e.g. music, whether written or spoken, audial or visual, based on some set of stylistic criteria. Genres are formed by conventions that change over time as new genres are invented and the use of old ones are discontinued. Often, works fit into multiple genres by way of borrowing and recombining these conventions. - http://en.wikipedia.org/wiki/Genre

The "Thriller" genre  is a very broad genre, it uses tension, suspense and excitement as it's main elements. The genre will often stimulate the viewers moods by adding a high level of anticipation as they don't see what is coming. Thrillers can be divided into sub genres such as "period thrillers", "pyschological thrillers", "conspiracy thrillers", "erotic thrillers","political thrillers", "pyschological thrillers", "spy thrillers" and "supernatural thrillers".

Conventions of the film noir genre:  
Characters and plots: The genre of film noir often revolves around men who are often flawed or questionable morally, they are also often down and out detectives or private eyes that are given a case by a beautiful but dangerous woman, this is a femme fatale. The plots are revolved around crime which is a key element in the noir genre.

Mise-en-scene: Noir movies are often based in urban citites such as New York, Los Angeles, San Francisco or Chicago, this is because the noir genre will make the city a "labirynth" or "maze" for the hero. Bars, nightclubs, lounges or gambling dens/casios will be heavily featured.  The lighting will be dark and almost silhouette characters this is a technique called chiaroscuro. The cars and fashion are often old fashioned.

Iconography:
Guns, cigarettes, smoke, alcohol, neon lighting, trilby's, cars, police iconography.

Themes: 
The Haunted Past… In the noir world both past and present are inextricably bound… One cannot escape one’s past… And only in confronting it can the noir protagonist hope for some kind of redemption, even if it is at the end of a gun.
The Fatalistic Nightmare. The noir world revolves around causality. Events are linked… and lead inevitably to a heavily foreshadowed conclusion. It is a deterministic universe in which psychology… and even the structures of society… can ultimately override whatever good intentions and high hopes the main characters may have. http://filmsnoir.net/film_noir/the-themes-of-film-noir.html