Many of you must have seen your cats scratching your curtains, carpets, sofas', couches, and much more. You must have tried to deal with the cats scratching your furniture in all the possible ways. Sometimes it becomes highly frustrating and irritating when you see your cat scratching, your brand-new table, or chair. Why do the cats love to scratch? Why are they so claw-ful?
Believe it or not, scratching is very usual and healthy behavior for cats. It is highly intuitive. They are always on the lookout for that perfect scratching spot. Not to worry, it a healthy habit too. 
Cats love to scratch for many reasons. Let us try to scratch out those reasons for ourselves –
1. To exercise
Cats love to stretch, and when they do so, they love to scratch. While scratching, the cats stretch out their back, legs, and paws, also flexing their claws and feet. Cats love to pamper themselves. So, while scratching, they remove the outer dead layer of their claws, clean, file, and sharpen them. No wonder they are so clean and tidy.
2. For Relieving Stress
Scratching is just like yoga for cats. When they scratch, they stretch their muscles and relieve any stress or tension in them. At the same time, they release 'feel-good' hormones, making them highly energetic and cathletic. These 'feel-good' hormones also help them to groom themselves and keep them paw-tastic. 
Find more beautiful cat scratch pads >>>
3. Marking a Territory
Scratching is communication for cats. When the cats scratch, they communicate with other cats, and us humans, trying to tell anyone and everyone that a cat lives here and that this is its territory. By leaving a mark visible on any of the visible surfaces or furniture of the house, it establishes possession of the territory. Why do they want to establish their territory? It is because cats feel relaxed in their own space as they like to stay aloof from everybody. In this way, it clarifies to other cats and animals that "Please do not enter. This house is mine".
4. Basic Instinct
Cats, after all, belong to a family of Wildcats. For them, it is natural to scratch. If they find a surface that feels and looks good, they will be attracted to scratch it. Interestingly the higher the cats scratch, the more dominant they are. Learn to respect the cat's instinct and provide them with alternatives options for scratching. 
5. A Safe Scent Marking
There are scent glands that are hidden in the cat's paws. When cats scratch, they use these secret scent glands to establish or mark their territories. We may find only a scratch on the surface, but along with the scratch, they also leave their scent, which effectively claims it as their turf. The glands secret Pheromones, detectable only to other cats and animals, leaving out humans. Thus, they create safe zones for themselves and give a clear message to the other animals that 'This is my home.'
What can one do to keep the cat from scratching desktop the stuff?
Here are some ways which can prevent the cats from scratching your favorite furniture and other stuff –
• Make your furniture scratch proof by installing specially designed furniture protectors
• Use repellent sprays with citrus or herb cents which are naturally repulsive but not harmful to cats
• Provide alternative scratching places like scratching posts or scratching mats or trees or rugs and keep them in strategic places where they usually scratch
• In case if the cat focuses more on the arms of the couches or chairs, then you can hang a scratcher or install scratch poles near it so that they can alternatively scratch on it
• Use catnip or treats as bait to divert their attention from scratching
• You can also install scratchers in a quiet, safe place for the cats to enjoy their scratching experience.
• Another idea is to wrap coir ropes around the furniture's legs to provide a good scratch for your cat.
• Cats love to scratch in the morning when they wake up. It will be a good idea to install a scratching post near its bed for that morning's scratch.
• Ensure having enough scratch posts installed all over your house to divert the Kitty from scratching on your favorite stuff
Last but not least, do not punish your kitten or cat for scratching your favorite furniture piece. Instead, be patient and try to redirect the cat to the nearest scratching post. With lots of purr-suasion, love, praise, support, and encouragement, your cat will surely learn soon enough that the best option to scratch is the scratching post best option.
Quoting Miguel de Cervantes (author, Don Quixote) - "Those who'll play with cats must expect to be scratched."