# Initial situation: Desktop application with Windows Presentation Foundation

Many desktop applications for the Windows operating system were created using the Windows Presentation Foundation (WPF) graphics framework. WPF offers a modern declarative way of creating user interfaces and supports a variety of features that simplify the development of complex applications. The technical foundations and concepts of WPF include:

* **XAML (eXtensible Application Markup Language):** XAML is a declarative markup language to define the user interface. It allows UI elements and their properties to be described structurally, supporting the separation of layout and logic.
* **Data Binding:** Data binding allows UI elements to be bound directly to data sources. This simplifies the synchronization of data between the user interface and the underlying data model.
* **Styling:** A style consists of a collection of properties that can be applied to one or more UI elements. This enables consistent UI design and simplifies changing the application's appearance.
* **UI Controls:** There are a variety of UI controls that can be used to create interactive user interfaces, such as Button, TextBox, ListView, and DataGrid. These controls are customizable and support data binding and styling.
* **Commands:** A command is an action triggered by the user interface and processed in the ViewModel or code-behind. It ensures the separation of user interface and logic.