It's extremely important for your cat to have a place where she can scratch her claws and wear off the layers of dead skin that cover them. A scratching post or board is best for this purpose. Especially for housebound cats, a scratching post is a must.
Sometimes a cat won't accept the scratching post intended for her. A reason for this could be simple inconvenience -- no cat wants to wander out of the cozy living room into an inconvenient spot to sharpen her claws. So the right location is of great importance. Another reason for rejecting the post may be the material it's made of; some cats prefer to sharpen their claws on sisal-rope posts.
The scratching post can serve as more than a manicuring station, it can be a good place to lie down and relax, and to play and climb. Some scratching posts come with built-in catnip to give your cat some extra fun. And a little ball or another toy will make the scratching post even more interesting. If you want to go all-out, many pet stores also sell elaborate cat trees that will give your cat (and you) hours of entertainment.