. What is the difference between having a method in a Model, Helper and a Controller?
Well, they are available in different places. You'd need to learn some Ruby surely before getting into Rails.
The Model-View-Controller (MVC) design pattern has been around for a long time. If you google for it you will find LOTS of information about it.
Having so much written about a topic can present a bit of a problem. The danger is that MVC is such an abstract concept that you'll see people "force fit" the idea into some areas where it really doesn't apply at all.
For example, one blog I ran across was attempting to apply MVC to the web itself. The article was saying the HTML is the model, CSS is the view and the web browser was the controller. Maybe is some twisted universe or other space-time dimension that's true, but in my interpretation of MVC that's pushing things a bit.
Anyway, my point is that there are many ways to apply MVC, but the pattern grew from the requirements of desktop application user interfaces. The pattern is very clear there (when used properly). Things get a little more fuzzy in the web development space.
One of the best documents I've read on MVC is actually in the Apple Cocoa Fundamentals document. It's not specifically related to Ruby, but it does a good job explaining the roles of objects in MVC.
Barun Anand wrote: