As you may recall, the Windows API (Win32) was a flat, unorganized collection of many thousands of confusing C-based functions. But the .NET Framework was—and still is—an object-oriented and organized hierarchical class library consisting of logical containers called namespaces. A namespace can contain other namespaces, classes representing various objects, most of which are further sub-classed to create more specific objects, and other items. Each object provides a variety of fields, properties, and methods for developers to access.

The .NET Framework’s hierarchical nature solved many of the problems with Win32, key among them that Win32’s flat, disorganized nature meant that every function name in the Windows API had to be unique. But once you move to a hierarchical system, that limitation disappears. Indeed, you will see the same method names in various classes throughout the .NET Framework. Every interactive control, for example, has a Click() method. What makes each unique is their fully qualified name, which includes their containing namespaces and classes.