There are several flavors of MVC. 

In the [original concept][1] published 1979, the view queries the model and the model doesn’t know about the views. However constant polling is not so efficient.

Subsequent [MVC designs ][2]therefore generally see the view as an [observer][3] of the model. This means that views subscribe to the model and get notified of changes. The model does not know that it’s a view and can not use the full view’s interface. You’ll find an in-depth analysis of the MVC relationships in [GoF][4] (page 4 to 6). 


  [1]: http://heim.ifi.uio.no/~trygver/themes/mvc/mvc-index.html
  [2]: https://en.m.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
  [3]: https://en.m.wikipedia.org/wiki/Observer_pattern
  [4]: https://en.wikipedia.org/wiki/Design_Patterns