Any type derived from the Object class can be assigned to this property. If the Tag property is set through the Windows Forms designer, only text can be assigned.

A common use for the Tag property is to store data that is closely associated with the control. For example, if you have a control that displays information about a customer, you might store a DataSet that contains the customer's order history in that control's Tag property so the data can be accessed quickly.

The following code example displays a form and stores a Customer in its Tag property. This example requires that you have defined a class that derives from Form named CustomerForm and that you have defined a Customer.

Private Sub buttonNewCustomer_Click(sender As Object, _
  e As EventArgs) Handles buttonNewCustomer.Click
   ' Create a new customer form and assign a new 
   ' Customer object to the Tag property. 
   Dim customerForm As New CustomerForm()
   customerForm.Tag = New Customer()
   customerForm.Show()
End Sub

private void buttonNewCustomer_Click(object sender, EventArgs e)
{
   /* Create a new customer form and assign a new 
    * Customer object to the Tag property. */
   CustomerForm customerForm = new CustomerForm();
   customerForm.Tag = new Customer();
   customerForm.Show();
}

private:
   void buttonNewCustomer_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      /* Create a new customer form and assign a new
                  * Customer object to the Tag property. */
      CustomerForm^ customerForm = gcnew CustomerForm;
      customerForm->Tag = gcnew Customer;
      customerForm->Show();
   }

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference