As you may know that cats love to scratch. In fact, they do it so frequently that many of us have to resort to buying scratching posts or mats so that they will not land their claws on our favorite furniture. The practice of clawing is a signature action of cats. They practice their nails every day for mainly 2 reasons:

Hone and sharpen the claws:

By scratching, cats can remove the worn and fraying outer layer of the nail and hone and sharpen the claws, keeping them in excellent shape and having them ready for self-defense or hunting. The clawing habit is innate, so even though your cat does not bring you dead rodents or birds, nor does he roam outside the house, you will still see him perform scratching gestures in a daily basis.

"This is my domain now":

Scratching is not just a way to shape their claws, it is done foremostly for marking their territory in the house. As they exercise their claws on the scratching post, they are leaving their marks and scent on the post to draw their turf from other cats in the same area and signal them that this is their domain now. Even though your cats may not scratch your furniture any more, rest assured, there is no stopping when it comes to marking territory. By rubbing and pawing on the furniture, they are leaving their body scent emitted from the pheromone glands situated on the paws and their face. Marking with their scent will help them familiarize with the area next time they come around. Their scent tells them that they are within their own territory and assures safety of themselves.