Added acronym and reference link for Model–view–controller

Conflicts:

	README.rdoc

README.rdoc

@@ -1,20 +1,24 @@
 == Welcome to Rails
 
 Rails is a web-application framework that includes everything needed to create
-database-backed web applications according to the Model-View-Control pattern.
-
-This pattern splits the view (also called the presentation) into "dumb"
-templates that are primarily responsible for inserting pre-built data in between
-HTML tags. The model contains the "smart" domain objects (such as Account,
-Product, Person, Post) that holds all the business logic and knows how to
-persist themselves to a database. The controller handles the incoming requests
-(such as Save New Account, Update Product, Show Post) by manipulating the model
-and directing data to the view.
-
-In Rails, the model is handled by what's called an object-relational mapping
-layer entitled Active Record. This layer allows you to present the data from
-database rows as objects and embellish these data objects with business logic
-methods. You can read more about Active Record in its
+
+database-backed web applications according to the {Model-View-Controller (MVC)}[http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller] pattern.
+
+Understanding the MVC pattern is key to understanding Rails.  MVC divides your application
+into three layers, each with a specific responsibility.
+
+The View layer is composed of "templates" that are responsible for providing 
+appropriate representations of your application's resources.  Templates
+can come in a variety of formats, but most view templates are HTML with embedded Ruby 
+code (.erb files). 
+
+The Model layer represents your domain model (such as Account, Product, Person, Post) 
+and encapsulates the business logic that is specific to your application. In Rails, 
+database-backed model classes are derived from ActiveRecord::Base. ActiveRecord allows
+you to present the data from database rows as objects and embellish these data objects 
+with business logic methods. Although most Rails models are backed by a database, models 
+can also be ordinary Ruby classes, or Ruby classes that implement a set of interfaces as
+provided by the ActiveModel module. You can read more about Active Record in its
 {README}[link:files/activerecord/README_rdoc.html].
 
 The controller and view are handled by the Action Pack, which handles both