Non-linear means that film can be assembled in any order from beginning to end, and editing changes can be made at any time and any place in the film. On the other hand, when you edit using video, an editor must begin the cut at the beginning of the program and lay down shots in a sequential order. Often an project edited in this way must make several versions of the program. You'll have to re-edit a film or video piece to add just one shot or special effect to your work. It's like using a typewriter. One mistake and you have to either white it out by coping over that part of the tape or completely throw out your work and re-edit the whole thing. You are also partially blind editing film in a linear fashion. You can only predict special effects like disolves, wipes and pushes and you have no way of seeing them until their printed on film. A film editor must make all his or her decisions without benefit of these effects, marking the work-print edit with grease pencil where the dissolves are supposed to go. As a flatbed film editor you have to break a splice in half and make changes in the middle of the film edit, but the disadvantages is that you have to keep track of thousands of little film trims. They are very scratchable and easily lost. Non-Linear Editing, in the context of computer editing, is to film and video editing what the word processor was to the typewriter. Non-linear editing combines the best of both film and video into one editor. A NLE allows you to change edits anywhere at any time. A NLE can save hours of work logging and archiving footage. A NLE can remember and undo your recent edits that you aren't happy with. A NLE can generate an Edit Decision List (EDL) for film (a "cut list") or video to be sent to a negative conformer or in the case of video, can be imported into a n edit controller. Most NLE's use all digital sound. Many NLE's allow you to do titles generation, dissolves, wipes, video and 3D effects, and other custom effects on-the-fly or in real time. Many NLE's allow you to convert to and from other computer formats for manipulation by other graphics programs (for morphing, matting, or other manipulation). Non-linear-editors are an AMAZING tool for an editor, both on film and video. There are literally dozens of non-linear editors on the market. Some companies have been in the business for longer than others, however. Non Linear Editing systems include AVID's Media Composer and Film Composer 8000, Data Translation's Media 100, LightWorks, the VideoCube, and D-Vision.