A XAML Package is a collection of files and resources that use XAML (Extensible Application Markup Language) to define the visual elements and layout of Windows applications. These packages help Windows systems render user interface components such as menus, buttons, and dialogs. By separating the visual design from the application logic, XAML Packages make it easier for developers to create, update, and maintain the look and feel of software. They are commonly used in Windows Presentation Foundation (WPF) and Universal Windows Platform (UWP) applications to deliver a consistent and flexible user interface experience.