Zoomed images are typically larger than the size of the document window. When this happens, Photoshop adds navigational scroll bars to the bottom and the right of the document window. However, using awkward scroll bars is not the only way to change the viewable area of the image; the Navigator palette gives you a visible approach to changing the view area of the image. The view box in the Navigator palette represents the visible boundaries of the active document window, which is the viewable area of the image.