When an object is scratched, loose nail sheaths may be detached thus fulfilling a grooming function. Scratching is usually directed at vertical surfaces, but not exclusively, and is usually performed with the forefeet only, although occasionally scratching using all four feet can be seen. A cat may stretch up to full height to reach and scratch with fairly large movements, one paw at a time. Alternatively, the limbs may be kept flexed with the paws close to the body and small individual pulling and lifting movements made with each paw alternately, almost demonstrating a kneading type action. See Chemical Communication.
The following sequence shows scratching on a horizontal surface. Look at how the claws of each foot are moved during the sequence.