WinUI 3.0 marks a new approach to delivering Windows UI components and controls, allowing you to use the same components in Windows 10 and future versions of this OS. Here is a detailed introduction to WinUI and the development of a Windows application for programmers starting to master WinUI, Universal Windows Platform (UWP) and XAML-based applications. After reading the book, you will understand how to write WinUI applications from scratch and how to upgrade existing WPF and WinForms applications by adding WinUI controls to them. The publication is addressed to everyone who wants to develop applications for Windows with a modern interface. If you are already familiar with UWP and WPF and want to enrich your knowledge and upgrade existing applications, then this book will be you. It is assumed that you have experience with the C # language and the .NET platform, but prior knowledge of WinUI is not required.