Traditionally, a jersey is an item of knitted clothing, generally made of wool or cotton, with sleeves, worn as a pullover, as it does not open at the front, unlike a cardigan. It is usually close-fitting and machine knitted in contrast to a guernsey that is more often hand knit with a thicker yarn. The word is usually used interchangeably with sweater. Alternatively, the shirt worn by members of a sports team as part of the team uniform is also referred to as a jersey.