Non-linear editing differs from linear editing in several fundamental ways.

First, video from the field tapes (or whatever the source is) is recorded to the editing computer's hard drive or RAID array prior to the edit session.

Next, rather than laying video to the recorder in sequential shots, the segments are assembled using a video-editing software program like Adobe Premier or After Effects.

Transitions (such as dissolves or wipes) can be placed between the segments. Also, most of these programs have some sort of CG or character generator feature built in for lower-thirds or titles.

The work-in-progress can be viewed at any time during the edit in real time. Once the edit is complete, it is finally laid to video.

Non-linear video editing removes the need to lay down video in real time. It also allows the individual doing the editing to make changes at any point without affecting the rest of the edit.