The document discusses the Model-View-Controller (MVC) architectural pattern. MVC separates an application's data model (Model), user interface (View), and control logic (Controller) to allow for more modular and cohesive systems. The model manages the application's data and business logic, the view displays the UI and outputs to the user, and the controller interprets user input and commands changes to the model or view. MVC promotes separation of concerns, loose coupling, and ease of maintenance. It originated in 1979 and was first used in Smalltalk-80 to develop graphical user interfaces like those of the Apple Lisa and Macintosh computers.