If your cat is near you, and her tail is quivering , this is the greatest expression of love your cat can give you. Cats wag their tails when it is in a stage of conflict. The cat wants to do two things at once, but each impulse blocks the other. The cat wants to go outside, but doesn't want to go into the rain. Once the cat makes a decision and either returns to the house or leaves into the rain, the tail will immediately stop wagging.
Cats knead with their paws when they're happy.
If you're sad or under stress, you may also notice a difference in your cat's behavior. The domestic cat is the only cat species able to hold its tail vertically while walking. All wild cats hold their tails horizontally or tucked between their legs while walking. During her productive life, one female cat could have more than 100 kittens. In 1952, a Texas Tabby named Dusty set the record by having more than 420 kittens before having her last litter at age 18.