The Model-View-ViewModel (MVVM) is a software design pattern that is structured to separate program (business) logic and user interface controls. The main advantage is, that the program logic is fully unit-testable as it functions independently of the UI controls (loosely coupled). It is very popular among the developers of XAML-based UI frameworks such as WPF, UWP, Xamarin.Forms, .NET MAUI, WinUI, and even other 3rd Party frameworks such as Uno.