The first 18 titles are the most important historical documentary films in establishing the genre, aesthetics, and issues of this genre.

Early documentary film critic, Grierson's principles of documentary were that cinema's potential for observing life could be exploited in a new art form; that the "original" actor and "original" scene are better guides than their fiction counterparts to interpreting the modern world; and that materials "thus taken from the raw" can be more real than the acted article. Grierson's definition of documentary as "creative treatment of actuality" has gained some acceptance, though it presents philosophical questions about documentaries containing stagings and reenactments.

With Robert J. Flaherty's Nanook of the North in 1922, documentary film embraced the artistic trends of romanticism (emotionalism, celebration of the traditional, human passions and shortcomings, etc.), Flaherty filmed a number of these documentary films during this time period, often showing how his subjects would have lived 100 years earlier and not how they lived right then. For instance, in Nanook of the North Flaherty did not allow his subjects to shoot a walrus with a nearby shotgun, but had them use a harpoon instead. Some of Flaherty's staging, such as building a roofless igloo for interior shots, was done to accommodate the filming technology of the time.

The continental, or realist, tradition of documentary film focused on humans within more civilized urban environments, and included the so-called "city symphony" films such as Walter Ruttmann's Berlin, Symphony of a City. Early film critic Grierson stated that Berlin represented what a documentary should not be. These films tend to feature people as products of their environment, and lean towards the avant-garde traditions of film-making.

Pare Lorentz's The Plow That Broke the Plains (1936) and The River (1938) and Willard Van Dyke's The City (1939) are notable New Deal productions, each presenting complex combinations of social and ecological awareness, government propaganda, and leftist viewpoints.

In Britain, a number of different filmmakers came together under John Grierson. They became known as the Documentary Film Movement and blended propaganda, information, and education with a more poetic aesthetic approach to documentary. Their work involved poets such as W. H. Auden, composers such as Benjamin Britten, and writers such as J. B. Priestley. Among the best known films of the movement are Night Mail and Coal Face.

Cinéma vérité (or the closely related direct cinema) was dependent on some technical advances in order to exist: light, quiet and reliable cameras, and portable sync sound. Cinéma vérité and similar documentary traditions can thus be seen, in a broader perspective, as a reaction against studio-based film production constraints. Shooting on location, with smaller crews, would also happen in the French New Wave, the filmmakers taking advantage of advances in technology allowing smaller, handheld cameras and synchronized sound to film events on location as they unfolded. Although the terms are sometimes used interchangeably, there are important differences between cinéma vérité (Jean Rouch) and the North American "Direct Cinema." The directors of the movement take different viewpoints on their degree of involvement with their subjects. The fundamentals of the style include following a person during a crisis with a moving, often handheld, camera to capture more personal reactions. There are no sit-down interviews, and the shooting ratio (the amount of film shot to the finished product) is very high, often reaching 80 to one. From there, editors find and sculpt the work into a film.

The films Primary and Crisis: Behind a Presidential Commitment (both produced by Robert Drew) and Harlan County, USA (directed by Barbara Kopple) are frequently deemed cinéma vérité films.

In the 1960s and 1970s, documentary film was often conceived as a political weapon against neocolonialism and capitalism in general, especially in Latin America.

The style of documentary films has expanded in the past 20 years from the cinema verité style introduced in the 1960s in which the use of portable camera and sound equipment allowed an intimate relationship between filmmaker and subject. The line blurs between documentary and narrative and some works are very personal, which mix expressive, poetic, and rhetorical elements and stresses subjectivities rather than historical materials. Historical documentaries, such as The Civil War by Ken Burns, expressed not only a distinctive voice but also a perspective and point of views. Some films such as The Thin Blue Line by Errol Morris incorporated stylized re-enactments

The remainder of this list are considered the best documentary films ever created.