Cat

From The Sims Wiki, a database for The Sims series that anyone can edit

Cats are pets that can be bought or sold in most Sims games. They are one of the most common pets you can own. In some games, such as the GBA Sims games, they are not something you need or have to take care of much, aside from petting them and and cleaning up their messes. They are mostly for show.

In other games, like The Sims: Unleashed and The Sims 2: Pets, they are one of the main parts of the game, in that they must be fed, given attention, played with, cleaned and watched over.

Cats also have to be trained so they can live with Sims. The player can do this by scolding them if they don't want them to do something that is bad, e.g destroying furniture, or you can praise them to continue doing it. Cats can be trained to be sloppy or neat.