• Namespace is logical division of class, structure and interface OR way to organize your Visual Basic .NET code is through the use of namespaces.
• Namespaces are a way of grouping type names and reducing the chance of name collisions.
• The namespace with all the built-in functionality comes under System namespace. All other namespaces comes under this System namespace.
  
  

  Declaration of Namespaces:

  // Namespace Declaration in C#
  • using System;
  • using System.Data;
  // Namespace Declaration in VB
  • imports system;
  • imports system.Data;
    
    
    

    Advantages:

    • We can establish security, version, reference, and deployment boundaries by using namespaces
    • Because of grouping of namespaces we can create hierarchy which is easy to identify classes by fully qualified names.
      
      
      Well If  you don't use Namespace in your application then you can import the library, for example suppose , if you want to bind gridview using sql server, for that you have you use:
      
      Sqlconnection
      SqlCommand
      dataTable
      SqlDataReader ..
      
      all these you have to use for binding purpose ,  to use this  you have to import these namespaces
      
      Using  System.Data;
    • Using  System.Data.SqlClient;

    If you will not use these  namespaces then in your application the intellisence of VS1o will not showing you the SqlConnection , and all the necessary code that requires in binding.
    
    
    error of namespace : [If you will not import the namespace]
    
    
     The type or namespace name 'MyControl' does not exist in the namespace 'MyNamespace' (are you missing an assembly reference?)
     
    
    

    
    
  
  

Need for Namespaces

Namespaces allow you to create a system to organize your code. A good way to organize your namespaces is via a hierarchical system. You put the more general names at the top of the hierarchy and get more specific as you go down. This hierarchical system can be represented by nested namespaces.By placing code in different sub-namespaces, you can keep your code organized.