problems about invoke method ?

I've viewed this link http://msdn.microsoft.com/en-us/library/zyzhdc6b.aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-1 .It talks about Invode method.And I haven't got clear about some points of this.As refered in the article : "The Invoke method searches up the control's parent chain until it finds a control or form that has a window handle if the current control's underlying window handle does not exist yet. If no appropriate handle can be found, the Invoke method will throw an exception. Exceptions that are raised during the call will be propagated back to the caller."

I don't understand some definitions such as "the control's parent chain", "a window handle", "if the current control's underlying window handle", so I hope someone gives me explainations about these ones !