FILM NOIR
So what is “film noir” anyway? Well, it’s French for “dark film”. Think L.A. Confidential (1997) or Chinatown (1974), two excellent fairly recent examples of film noir: World-weary heros, underworld types, very bad girls with hearts of lead, lots of smoky atmosphere. To paraphrase Justice Stewart on pornography, you’ll know a film noir  when you see one (and when you do see one you’ll have a good time!)
Hollywood keeps trying out variations on the film noir formula, often with good success. But the classic film noir movies were made from 1937-1950. The most famous, and one of the best, is The Maltese Falcon (1941). With Humphrey Bogart as Sam Spade, a private eye who’s been around the block too many times, Mary Astor as his glamorous employer, and Sidney Greenstreet and Peter Lorre as very bad guys, this is a superb cast. The ambivalent ending is just right, the stuff that dreams are made of.
This Gun For Hire (1942) features Alan Ladd as a small time thug bent on revenge, and made him a star. Veronica Lake is the quintessential film noir bad girl and Robert Preston (The Music Man himself) shows what he can do as the bad guy. The story keeps your interest, but it’s the characters that really shine.
Humphrey Bogart and Lauren Bacall are an unbeatable combination and practically set the screen on fire in The Big Sleep (1946). From a Raymond Chandler story with a screenplay by no less than William Faulkner (among others) the dialogue is just marvelous. The plot is so convoluted no one can figure out who did what to whom, but then it’s so much fun that nobody cares.
Robert Mitchum was probably the definitive film noir leading man. Those hooded eyes and that whiskey voice are put to great use in Out Of The Past (1947). Mitchum finds he cannot escape his thuggish history and becomes involved with mobster Kirk Douglas and bad girls Rhonda Fleming and Jane Greer in very criminal matters. 
In Force of Evil (1948) the much underrated John Garfield is superb as a criminal lawyer for the mob, whose morals have gone over the hill. Marie Windsor (My Friend Irma!) is the girl. Beautifully photographed in black and white; not to be missed.
Perhaps the last entry from the classic age of films noir is Touch Of Evil (1948).
It was directed by and starred Orson Welles, who absolutely exudes evil as a corrupt cop. Charlton Heston (with a moustache!) and Janet Leigh add to the cast of a film that is as dark as they get. 
Other good examples of film noir: Criss Cross (1949), Crossfire (1947), In A Lonely Place (1950), and They Live By Night (1949). All of the movies in this article are available on DVD.  All are for those 12 and up.