Developing graphical user interfaces in C# can feel overwhelming with so many frameworks and tools to choose from. This book simplifies the journey by teaching GUI fundamentals through small, structured, and practical examples. You start with core GUI concepts, event driven programming, and basic interface design. Then you build simple web apps using Blazor and WebAssembly, learning about components, rendering, and data binding. Next, you explore cross platform development with .NET MAUI, working with XAML, layouts, controls, and basic app logic. Finally, you create Windows desktop applications with WinUI 3, using common controls and foundational patterns such as MVVM and data binding. Rather than focusing on complex enterprise architecture, the book builds your skills step by step. Each chapter reinforces key ideas through clear examples designed to build confidence and practical understanding. Written by Marcelo, a developer with over 18 years of experience in C#, C++, Azure, and data driven systems, this book helps you gain clarity in GUI development. By the end, you will be able to create simple, well structured web and desktop interfaces in C# and understand the core concepts behind them.