The movie was written by John W. Cunningham (story) and Carl Foreman, based on a pulp short story, The Tin Star. It was directed by Fred Zinnemann, a controversial choice, since the producers were uncertain that an Austrian Jew would be able to direct the quintessential American genre: the Western. Zinnemann himself was highly influenced by the books of Karl May that he had read as a child.
Warning: Wikipedia contains spoilers.
High Noon is a generally praised but somewhat controversial western in which a lawman in a western town feels obliged to face down a bunch of bad men coming into town. Cooper's character is betrayed by all the "good" men in town who won't take up arms for a good cause. It is often an interpreted as an allegory of contemporary mccarthyism.
There was some controversy over the casting of Gary Cooper in the lead role. Although he had already won an Oscar for his performance in Sergeant York, he was considered too old for the part, and was, in fact, thirty years older than Grace Kelly, who plays his wife.
In the film she is a young woman who wants her husband to leave town and has a religious aversion to violence of any kind. Still, she stays with him when he fights -- and even kills one of her husband's assailants herself.
The movie won Academy Awards for Best Actor in a Leading Role (Gary Cooper), Best Film Editing, Best Music, Scoring of a Dramatic or Comedy Picture (Dimitri Tiomkin), and Best Music, Song (Dimitri Tiomkin and Ned Washington for High Noon (Do Not Forsake Me, Oh My Darlin'), sung by Tex Ritter). It was nominated for Best Director, Best Picture, and Best Writing, Screenplay.
One of the interesting techniques used in filming High Noon was to have the sequence of events occur in "real time." When a clock is shown in a scene, an event the audience expects to occur at another given time will occur that number of minutes later in the movie.
The director intended to capture the atmosphere of old Civil War photographs, with an austere gray sky as a backdrop. Despite the constraints of a limited budget ($750,000) and only 28 days to film, he was able to obtain this even though most of the film was shot in a Hollywood lot by taking advantage of the smog in Los Angeles to darken the sky.
High Noon is consistantly on the Internet Movie Database's list of top 250 films, was #33 on American Film Institute's 100 Years, 100 Movies, and has been selected for preservation in the United States National Film Registry. Its haunting theme music is still popular.
A made-for-TV sequel, "High Noon Part II: The Return Of Will Kane" (produced in 1980, 28 years after the original movie was released), featured Lee Majors in the Cooper role.
And finally, in 2000, "High Noon" was entirely re-worked for cable television with Tom Skerritt in the lead role.