Sportswear or Activewear is clothing, including footwear, worn for sport or exercise. Typical sport-specific garments include shorts, tracksuits, T-shirts, polo shirts and trainers. It also includes some underwear, such as the jockstrap. Sportswear is also often worn as casual fashion clothing. For most sports the athletes wear a combination of different items of clothing, e.g. sport shoes, pants and shirts.

Almost every piece of sports clothing is designed to be light weight so the athlete is not encumbered by its weight. The best athletic wear for some forms of exercise, for example cycling, should not create drag or be too bulky. On the other hand it should be loose enough so as not to restrict movement. Standardised sportswear may also have the function of a uniform. In team sports the opposing sides are usually made identifiable by the colours of their clothing, while individual team members can be made recognisable by a back number on a shirt. In hot weather garments should allow the wearer to stay cool. In cold weather garments should help to stay warm. In cold climates the best athletic wear should not only provide warmth but also transfer sweat away from the skin. For activities such as skiing and mountain climbing this is achieved by using layering: moisture transferring materials must be worn next to the skin, followed by an insulating layer, and wind and water resistant shell garments.