A cat scratches to keep its nails in good condition, to remove scent marks, to make scratches that other cats can see, and to react to stress. A scratching post near the cat’s favorite sleeping place is a godsend.
The scratching post should be stable and high enough (cat should be able to stretch standing up). Often preference is given to a vertical running fabric of not too firmly woven material (long strokes are then not possible). Some valerian dripping on top of the scratching post has an extra stimulating effect.