The PlaceHolder control can be used as a container control within a document to dynamically load other controls. The PlaceHolder control has no HTML based output and is used only to mark a spot for other controls that can be added to the control collection of the PlaceHolder during Execution. This control is used to preserve space for controls added by code. This control remains invisible when added to the page. The advantage of using PlaceHolder control is that the TextBox, Button and other content contained within the PlaceHolder opening and closing HTML Tags are Kept as a Single Entity.
Class Hierarchy for PlaceHolder control:-