MVC

Model-View-Controller (MVC) is a software architectural pattern that organizes an application into three interconnected components: the Model, the View, and the Controller. The Model represents the data and the business rules associated with that data. The View renders the user interface and presents data from the Model. The Controller handles user input, coordinates updates to the Model, and selects the appropriate View for response.

In typical MVC use, the View reads data from the Model to display to the user, often observing the Model for changes. The Controller receives input such as user actions or requests, updates the Model accordingly, and may switch the View to reflect the new state. The pattern encourages separation of concerns by isolating data and logic from the presentation layer.

MVC originated in the 1970s with Trygve Reenskaug at Xerox PARC and was popularized by Smalltalk environments. It has influenced many web and application frameworks, including Ruby on Rails, ASP.NET MVC, and Django's MTV variant. Variants and related patterns exist, such as Model-View-Presenter (MVP) and Model-View-ViewModel (MVVM), which adjust the direction of interaction between components.

Advantages of MVC include improved modularity, testability, and parallel development, as well as easier maintenance by isolating concerns. Drawbacks can include added complexity for small or simple interfaces, potential for controllers to become large or “fat”, and inconsistent interpretations of the pattern across frameworks. Migrating legacy code to MVC can also be challenging if the original design did not separate concerns clearly.