Cats' claws are part of their balancing mechanism, which is why they are able to spring high onto a surface and remain there without falling. If they do fall or the leap is too far, they can catch hold of some surfaces, such as tree bark, with their claws and thus save themselves from a tumble to the ground. Apart from the extremes of leaping and climbing, the claws provide balance for normal walking, running and stretching. In addition, the claws are the cat's weapons, for use against other animal, or indeed human, threats and enable them to dig so that this fastidious creature can cover up it's toilet area with fresh earth.
Cats scratch objects to mark their territories. There are glands in their paws containing a secretion, which transfers to the scratched area and which is detectable by other cats, although not by human noses. They also scratch to remove the old, rough-edged claw which falls off to reveal a new claw beneath.
Cats' claws are part of their balancing mechanism, which is why they are able to spring high onto a surface and remain there without falling. If they do fall or the leap is too far, they can catch hold of some surfaces, such as tree bark, with their claws and thus save themselves from a tumble to the ground.
It beggars belief that a person will put their own possessions above the contentment of their pet, but it is a fact that this does happen. Some humans (fortunately, relatively few), in their own selfish way, don't want their expensive furniture or carpets ruined by a scratching cat, so they solve the problem by having the cat's claws surgically removed. This can only be done by a vet and many vets will require a medical reason to do so and will not pander to the vanity of a human. However, some will undertake the required operation, particularly if the alternative is the destruction or re-homing of the cat and others just have no scruples at all.
In addition, cat owners should be aware that de-clawing a cat can change its personality completely. It may be in pain and it will certainly be confused. It may not be able to jump at all even onto the armchair or the window sill and it may not be able to enjoy a game of football. It may become introverted or even aggressive (it will still have teeth, so beware). In short, it will be miserable and you will be the cause - can you really live with that?