A mat is described which is suitable for placement over the threshold of an opening for protecting the threshold and nearby floor or other surface from excessive wear caused by pets or foot traffic. The perimeter edge of the mat in one embodiment includes a cutout or contour that is sized and shaped to at least partially engage the side post or jamb near the opening. One or both ends of the mat may include a contour that is shaped to engage the side jamb. The contour in another embodiment includes a slot that at least partially engages the wall near the opening. Engagement between the contoured edge of the mat and the side post or wall helps resist unintended movement of the mat when in place. The mat may also include downward protrusions for engaging with the floor or floor covering.