The Model-View-Controller (MVC) architectural pattern separates an app into three main components: **M**odel, **V**iew, and **C**ontroller. The MVC pattern helps you create apps that are more testable and easier to update than traditional monolithic apps. MVC-based apps contain:
* **M**odels: Classes that represent the data of the app. The model classes use validation logic to enforce business rules for that data. Typically, model objects retrieve and store model state in a database. In this tutorial, a `Movie` model retrieves movie data from a database, provides it to the view or updates it. Updated data is written to a database.
* **V**iews: Views are the components that display the app's user interface (UI). Generally, this UI displays the model data.
* **C**ontrollers: Classes that handle browser requests. They retrieve model data and call view templates that return a response. In an MVC app, the view only displays information; the controller handles and responds to user input and interaction. For example, the controller handles route data and query-string values, and passes these values to the model. The model might use these values to query the database. For example, `http://localhost:1234/Home/About` has route data of `Home` (the controller) and `About` (the action method to call on the home controller). `http://localhost:1234/Movies/Edit/5` is a request to edit the movie with ID=5 using the movie controller. We'll talk about route data later in the tutorial.
The MVC pattern helps you create apps that separate the different aspects of the app (input logic, business logic, and UI logic), while providing a loose coupling between these elements. The pattern specifies where each kind of logic should be located in the app. The UI logic belongs in the view. Input logic belongs in the controller. Business logic belongs in the model. This separation helps you manage complexity when you build an app, because it enables you to work on one aspect of the implementation at a time without impacting the code of another. For example, you can work on the view code without depending on the business logic code.
We cover these concepts in this tutorial series and show you how to use them to build a movie app. The MVC project contains folders for the *Controllers* and *Views*.
