Namespaces (C# Programming Guide)
Namespaces are heavily used in C# programming in two ways. First, the .NET Framework uses namespaces to organize its many classes, as follows:
System is a namespace and Console is a class in that namespace. The using keyword can be used so that the complete name is not required, as in the following example:
For more information, see using Directive (C# Reference).
Second, declaring your own namespaces can help you control the scope of class and method names in larger programming projects. Use the namespace keyword to declare a namespace, as in the following example:
Namespaces have the following properties:
They organize large code projects.
They are delimited by using the . operator.
The using directive obviates the requirement to specify the name of the namespace for every class.
The global namespace is the "root" namespace: global::System will always refer to the .NET Framework namespace System.
See the following topics for more information about namespaces:
For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.