Cats are adult kittens. They're like dogs but usually smaller and more liquid—dogs are more rigid.
Cats, unlike dogs, cannot be trained. They basically just do what they want. This usually involves clawing furniture and sleeping. They also intermittently make a large amount of noise, even sometimes in the middle of the night—they are crepuscular by nature and are therefore most active at dusk and dawn. In the meantime, they just sort of do whatever.
If you are responsible for a cat's well-being, you will need to provide it with fresh water, cat's food, and a box in which to deposit its poops. You will also need to pet it as much as you can.
Some cats are quiet; some are not. If you encounter a cat outside of a house and it isn't smallish, you might be dealing with a big cat (e.g. a jaguar, a bobcat, or a lion) which is a different danger situation altogether.
In general, cats are mostly cute, even if they are also sometimes annoying. Because you basically can't influence their behavior, you're sort of at their mercy and whim. They have sharp ends on their feet and inside their mouths, which can cause damage to flesh and fabric, and they will maybe pee on your textiles, but they do this more out of a predisposition towards contrarianism than as an actual aggression.
Because cats are cute but tend to fuck with you, we consider cats a little dangerous.
