Rats are very easy pets to care for. They need a cage, food, and water; the cage needs to be cleaned, and the rats need to be taken out and played with regularly, taking care that they don't escape and hide within the bowels of the sofa. They're very intelligent and affectionate, and you can teach them amusing tricks and turn them into circus rats, if you have lots of spare time and enjoy that sort of thing.

The big drawback is that their natural lifetime is very short-- four years maximum, and usually three. That's the other reason I stopped keeping them.