Kneading is the motion cats make by rhythmically alternating their paws, pushing in and out against a pliable, soft object (such as a lap). Not all cats knead in the same way; some never push out their claws at all, and some even use all four paws.
So Why Does My Cat Knead Me?
While not all cats knead, it is a common behavior for young and adult felines alike, so it's likely your cat does it. There are a few different ideas out there as to why. Some cats knead (and purr contentedly) when they’re being petted, but they may also do it for no clear reason. Let’s take a look at some of the more popular theories.
Kid at Heart
Cats start to knead as kittens, before they’re even able to get around on their own, while nursing from their mother. A nursing kitten instinctually kneads to help stimulate the mother’s milk production. Why do they continue to knead past nursing age? Even though kneading a soft surface doesn’t yield milk, adult cats forever associate the motion of kneading with the rewarding comfort of nursing.
If your cat is curled up and kneading your lap while you’re petting him, he’s returning the affection and telling you he loves you right back. Unfortunately, this can be quite painful, since the happier he is, the harder he’ll dig in with his sharp nails. Try placing a thick, soft barrier between the cat and your lap, or gently place him on his back and pet his belly if it gets too intense. However, do not punish your cat for this behavior -- he doesn't relaize it hurts. To better ensure the comfort of both you and your cat, make a habit of keeping his nails trimmed with cat nail clippers, or invest in nail guards to cover your cat's nails.
Cats are natural yoga masters and love to work out all the kinks left over from napping. Think about it — if you have sore shoulders, it feels good to grab onto a surface and pull against it. Kneading is one of the many ways cats keep themselves limber … until the next nap.
The wild ancestors of domestic cats liked to lay down on soft, comfortable surfaces to either sleep or give birth to their young. By kneading down tall grass or leaves, cats were able to fashion a comfy spot to lay down in, and also possibly to check the ground for unwelcome visitors lurking under the foliage.