In user interface design, a placeholder or an outline appears just below the label or the tool to show you where the new control object will be placed. This indicator helps designers to see where they can insert the control on the layout before finalizing the position.
When you are working with control objects in a visual design environment or a user interface (UI) design tool, the indication of where a new control will be placed is typically shown by a placeholder or an outline. This placeholder appears just below the label or the tool from which you are dragging the control. It may appear as a dashed box or a highlighted area within the target layout, signaling to the designer where the control can be inserted. Once the control is placed, this temporary indicator will usually disappear, leaving only the newly added control in the designated area.