1. NAMESPACE

2. Namespaces Namespaces are a way to define the classes and other types of information into one hierarchical structure. System is the basic namespace used by every.NET code. If we can explore the System namespace little bit, we can see it has lot of namespace that uses the system namespace. For example, System.IO, System.Net, System.Collections, System.Threading, etc. A namespace can be created via the Namespace keyword.

3. The Namespace Hierarchy and Fully-Qualified Names For example, the Button type is contained in the System.Windows.Forms namespace.

5. Namespace Namespace1 Public Class Class1 'class code End Class End Namespace

6. Imports alias directives. A Imports-alias-directive introduces an identifier that serves as an alias for a namespace or type within the immediately enclosing compilation unit or namespace body. Imports identifier = namespace-or-type-name; Within member declarations in a compilation unit,the identifier introduced by the Imports-alias- directive can be used to reference the given namespace or type.

7. Some Namespaces and their use: System: Includes essential classes and base classes for commonly used data types, events, exceptions and so on System.Collections: Includes classes and interfaces that define various collection of objects such as list, queues, hash tables, arrays, etc System.Data: Includes classes which lets us handle data from data sources System.Data.OleDb: Includes classes that support the OLEDB.NET provider System.Data.SqlClient: Includes classes that support the SQL Server.NET provider System.Diagnostics: Includes classes that allow to debug our application and to step through our code

8. System.Drawing: Provides access to drawing methods System.Globalization: Includes classes that specify culture-related information System.IO: Includes classes for data access with Files System.Net: Provides interface to protocols used on the internet System.Reflection: Includes classes and interfaces that return information about types, methods and fields System.Security: Includes classes to support the structure of common language runtime security system

9. System.Threading: Includes classes and interfaces to support multithreaded applications System.Web: Includes classes and interfaces that support browser-server communication System.Web.Services: Includes classes that let us build and use Web Services System.Windows.Forms: Includes classes for creating Windows based forms System.XML: Includes classes for XML support