A running board is a car or truck accessory part, comprising a narrow step fitted below the side doors of the vehicle. It aids entry, especially into high vehicles. Typical of vintage cars which had much higher ground clearances than today's cars, it is also used as a fashion statement on modern vehicles that would not require them. Sometimes they can also be structural parts of the vehicle.
Running boards may also be used to stand on while the vehicle is moving, though this has a high risk of injury from falling off.