Film editing is described as an art or skill, the only art that is unique to cinema, separating filmmaking from other art forms that preceded it, although there are close parallels to the editing process in other art forms such as poetry and novel writing.
Film editing is often referred to as the “invisible art” because when it is well-practiced, the viewer can become so engaged that he or she is not aware of the editor’s work.
On its most fundamental level, film editing is the art, technique, and practice of assembling shots into a coherent sequence. The job of an editor is not simply to mechanically put pieces of a film together, cut off film slates, or edit dialogue scenes. A film editor must creatively work with the layers of images, story, dialogue, music, pacing, as well as the actors’ performances to effectively “re-imagine” and even rewrite the film to craft a cohesive whole. Editors usually play a dynamic role in the making of a film. Sometimes, auteurist film directors edit their own films, for example, Akira Kurosawa, Bahram Beyzai, and the Coen Brothers. Read more at Wikipedia.