MVCに説明を追加

It is the idea that the essential part of the program, the model, is left when we remove the parts relating to display and parts related to the operation from the program.

When programmers think about a program, they tend to focus on view and controller.

Because it is easy to observe.

However we should not forget there is an important part. That is called "model."

The "model" is independent to the appearance of program and how user manipulate it.

The "model" holds information needed for the program to work.

(Not yet rewrited)