WPF
Windows Presentation Foundation (WPF) is a UI framework developed by Microsoft for building desktop applications on Windows. It uses XAML for declarative UI design and provides a rich set of controls, data binding, styling, and animation capabilities. WPF applications are typically written in C# or VB.NET and run on the .NET Framework or .NET Core/.NET 5+.
Developers should learn WPF when building modern, visually rich Windows desktop applications that require complex UI interactions, data visualization, or custom controls. It's ideal for enterprise applications, business software, and tools where a native Windows experience with advanced graphics and data binding is needed. WPF is particularly useful when leveraging the MVVM pattern for maintainable code separation.