The role of the model in MVVM

Question

I\'ve read a few articles regarding the role of the (Data)Model in the MVVM pattern. However, i still could not figure what goes into the model.

Should the model imp

Answer 1

In some cases a Model must implement INotifyPropertyChanged. Imagine that you are coding client for ICQ or something like that. How is the ViewModel supposed to know, that somebody send you a message?

Difference between Model and ViewModel:

A ViewModel only simplifies the output from a Model. If the model is very simple, a ViewModel isn't necessary.