When we watch a film, most of us have great difficulty in consciously perceiving the editing. Of course we know that every time there is a shift from one image to another, it is an edit, and we know that editing in general has to do with the establishing of rhythm in film. But we are often not sure of the concrete function of editing, and likewise of the contribution the editing process makes to the final film.
Therefore it is difficult for us to define what we mean when we discuss film editing in a specific film; when we try to categorise the different functions of film editing, we tend to mix up the issues.
For a film editor it is a cause for frequent amusement and/or irritation, that film reviewers are never able to point out the editor's contribution. If a film is described as very effectively cut but otherwise long and boring, the editor knows that the film may have contained conspicuous transitions of scenes that were invented during the shooting or in the scriptwriting, but that the editing was ineffective or even sloppy.
On the other hand many editors tend to ignore the fact that the concrete process of editing is not identical with film editing in general, and that film editors are not the only ones to contribute to the editing of the film.
The phenomenon of editing deals with all aspects of filmic rhythm - from the transition of one image to another or the detailed musical rhythm in a small sequence of edits, to the most general balancing of pace and rhythm in the overall narrative structure.
Major aspects of the editing of a film are created outside the editing room. The editor may be primary contributor in some areas of the editing, but the scriptwriter, the photographer and of course the director are also involved in determining the editing of a film.
Editing is a means of expression, with its own language. This language is created in the editing room as well as in the script writing process and on the set. And the editing usually works best if it is completely integrated with the other means of expression used in the given film.