About Linear and Non Linear

Linear vs Non Linear Editing
In the early days of electronic video production, linear (tape-to-tape) editing was the only way to edit video tapes. Then, in the 1990s, non-linear editing computers became available and opened a whole new world of editing power and flexibility.

Non-linear editing was not welcomed by everyone and many editors resisted the new wave. In addition, early digital video was plagued with performance issues and uncertainty. However, the advantages of non-linear video eventually became so overwhelming that they could not be ignored.

In the 21st Century non-linear editing is king and linear editing is widely considered to be obsolete, or at least primitive. This is an understandable attitude considering the advantages of non-linear editing, but we urge you not to be too judgemental. Linear editing still has some advantages:

It is simple and inexpensive. There are very few complications with formats, hardware conflicts, etc.
For some jobs linear editing is better. For example, if all you want to do is add two sections of video together, it is a lot quicker and easier to edit tape-to-tape than to capture and edit on a hard drive.
Learning linear editing skills increases your knowledge base and versatility. According to many professional editors, those who learn linear editing first tend to become better all-round editors.
Although the “linear vs non-linear” argument is often subjective and some editors will disagree with the statements above, there can be little doubt that increasing your skill base is a good thing. There is nothing to be gained by completely rejecting linear editing, and much to be gained by adding it to your repertoire.
From: http://www.mediacollege.com/video/editing/linear/linear-vs-nonlinear.html