Nested Namespaces in C#

Following example shows that one namespace can be nested within another:

using System;
using System.Windows.Forms;
 
namespace FirstNameSpace
{
    class Class1
    {
        public void ShowMessage()
        {
            MessageBox.Show("Class1");
        }
 
    }
    namespace SecondNameSpace
    {
        class Class2
        {
            public void ShowMessage()
            {
                MessageBox.Show("Class2");
            }
        }
    }
}
class Class3
{
    FirstNameSpace.Class1 cls1 = new FirstNameSpace.Class1();
    FirstNameSpace.SecondNameSpace.Class2 cls2 = new FirstNameSpace.SecondNameSpace.Class2();
}

Iin the program,the namespace FirstnameSpace is nested within SecondNameSpace.Thus to refer Class2 , we must qualify it with both namespaces.