Post-production according to Wikipedia
There are several editing stages and the editor’s cut is the first. An editor’s cut (sometimes referred to as the “Assembly edit” or “Rough cut”) is normally the first pass of what the final film will be when it reaches picture lock. The film editor usually starts working while principal photography starts. Likely, prior to cutting, the editor and director will have seen and/or discussed “dailies” (raw footage shot each day) as shooting progresses. Screening dailies gives the editor a ballpark idea of the director’s intentions. Because it is the first pass, the editor’s cut might be longer than the final film. The editor continues to refine the cut while shooting continues, and often the entire editing process goes on for many months and sometimes more than a year, depending on the film.
When shooting is finished, the director can then turn his full attention to collaborating with the editor and further refining the cut of the film. This is the time that is set aside where the film editor’s first cut is molded to fit the director’s vision. In the United States, under DGA rules, directors receive a minimum of ten weeks after completion of principal photography to prepare their first cut.
While collaborating on what is referred to as the “director’s cut”, the director and the editor go over the entire movie with a fine-tooth comb; scenes and shots are re-ordered, removed, shortened and otherwise tweaked. Often it is discovered that there are plot holes, missing shots or even missing segments which might require that new scenes be filmed. Because of this time working closely and collaborating – a period that is normally far longer, and far more intimately involved, than the entire production and filming – most directors and editors form a unique artistic bond.
Often after the director has had his chance to oversee a cut, the subsequent cuts are supervised by one or more producers, who represent the production company and/or movie studio. There have been several conflicts in the past between the director and the studio, sometimes leading to the use of the “Alan Smithee” credit signifying when a director no longer wants to be associated with the final release.