Cat Scratching
Doors, curtains, furniture and walls can all fall victim to your cat’s claws. The reasons behind scratching are quite interesting, and have nothing to do with sharpening those claws. In fact the only thing a cat has to do to keep his claws sharp is retract them while walking on hard surfaces, which all cats do anway. Scratching has other more useful purposes.
Renewing
Cats’ claws grow from the inside, and the outer layers are shed as the claw outgrows them. Scratching helps these layers fall off quicker, as evidenced by the number of shards of claw at the bottom of a favourite scratching station.
Territory
Scratching leaves marks for other cats to see, and a scent for them to smell. It lets them know they are in an area patrolled by another cat.
Exercise
When a cat is scratching, every muscle from the shoulder to the claws is being loosened, warmed up, and kept supple. In particular, the muscles that retract and extend the claws get a proper workout, in readiness for the next hunt, or the next time a little mouse-shaped toy needs playing with!