Documentaries are films that attempt to document real life. They have a specific focus, and are usually educational. Documentaries spent most of their history as educational or propaganda films. The modern box office has seen an influx of popular documentaries. This can be attributed to the popularity of reality television. Production companies like to create documentaries because of the low budget and increasing popularity.

The first documentary films were created in the late 1920's by the director John Grierson. He sought to create a new kind of art which was an observation of life. He felt that the documentary was a more pure form of art than the narrative style of film which was becoming popular. A narrative tells a story and has a distinct beginning and ending, usually with a climax and resolution. Documentaries generally do not tell stories. They have a focus, contain footage that deals with that focus. They may contain spontaneous interviews and unauthorized footage of real-life situations.

Documentaries have become increasingly popular. Directors like Michael Moore have had cult hits with documentary films like "Rodger and Me" (1989) and "Bowling for Columbine" (2002). This popularity lead to a major movie market for documentaries like "Super-Size Me" and "March of the Penguins". Documentaries may be shown in the theater, but more often they are released as documentary DVD's. Movie-lovers like this format because it is has high definition and often contains extra features which give even deeper insight into the focus of the film.