A sweater, pullover, jumper, or jersey is a relatively heavy shirt intened to cover the torso and arms of the human body (though, in some cases, sweaters are made for dogs and occasionally other animals) and typically to be worn over a shirt, blouse, T-shirt or other top. Sweaters tend to be, and in earlier times always were, made from wool (typically of sheep, though possibly of alpaca or other type); however, they can be made of cotton, synthetic fibres, or some combination thereof. Sweaters are maintained by washing, and the use of a lint roller.