Sportswear or activewear is clothing, including footwear, worn for sport or physical exercise. Sport-specific clothing is worn for most sports and physical exercise, for practical, comfort or safety reasons.
Typical sport-specific garments include shorts, tracksuits, T-shirts, tennis shirts and polo shirts. Specialized garments include wet suits (for swimming, diving or surfing) and salopettes (for skiing) and leotards (for gymnastics). Sports footwear include trainers. It also includes some underwear, such as the jockstrap and sports bra. Sportswear is also at times 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. In some sports, protective gear may need to be worn, such as helmets or American football body armour.
Functional considerations 
Sportswear is typically designed to be light weight so as not to encumber the wearer. The best athletic wear for some forms of exercise, for example cycling, should not create drag or be too bulky.
On the other hand, sportswear should be loose enough so as not to restrict movement. Some sports have specific style requirements, for example the keikogi used in karate. Various physically dangerous sports require protective gear, e.g. for fencing, American football, or ice hockey.
Standardized sportswear may also function as a uniform. In team sports the opposing sides are usually identified by the colors of their clothing, while individual team members can be recognized by a back number on a shirt.
Thermal properties 
Sportswear design must consider the thermal insulation needs of the wearer. In hot situations, sportswear should allow the wearer to stay cool; while in cold situations, sportswear should help the wearer to stay warm.
Sportswear should also be able to transfer sweat away from the skin, using, for example, moisture transferring fabric. Spandex is a popular material used as base layers to soak up sweat. For example, in activities such as skiing and mountain climbing this is achieved by using layering: moisture transferring materials are worn next to the skin, followed by an insulating layer, and wind and then water resistant shell garments.
Moisture-wicking fabrics 
Moisture-wicking fabrics are a class of hi-tech fabrics that provide moisture control for an athlete's skin. They move perspiration away from the body to the fabric's outer surface where it can evaporate. These fabrics typically are soft, lightweight, and stretchy—in other words, they are perfectly suited for making activewear. This broad category of fabrics is used to make garments like T-shirts, sports bras, running and cycling jerseys, socks, tracksuits, and polo-style shirts for any physical activity where the goal is to keep your skin as cool and dry as possible. Moisture-wicking fabrics are used to make apparel for outdoor activities such as hiking, fishing, mountain biking, snow skiing, and mountain climbing. Due to the popularity of garments made from these fabrics, more variations are being introduced to the market.
Golf attire 
Golf has a long tradition of specialized attire—attire that reflects the tradition of Scottish aristocrats taking in fresh air while walking around the golf course, swinging their golf clubs, and exercising in a refined, genteel sort of way. Golf attire though, is also being influenced by modern fabrics and trends that stress function and durability. Golfers, like athletes in other sports, are athletes first, and public figures second. Athletes in all sports are showing a preference for moisture-wicking fabrics, crisp details, and modern fashionable colors.
The most recognizable names in golf attire are: Golfsmith, Callaway, Titleist, Oakley, Nike Golf, PGA Championship Apparel, Under Armour, Tommy Hilfiger, Chaps, Jack Nicklaus, Puma, and Tiger Woods.
Sales trends for activewear 
As activewear becomes more fashionable and more popular with consumers, sales have increased. Total U.S. sales of men's and women's activewear rose by 3.2% in the 12 months ending in March  compared with the previous period, to $48.6 billion, according to consumer tracking firm NPD Group Inc. Apparently there are a lot of women who have no trouble spending nearly $100, and sometimes more, for a pair of workout pants they think will make them look stylish whether they're jogging or running errands. For all of 2011, activewear sales increased 6.7% from 2010, compared with women's apparel gains in 2011 of 3.1%, also according to NPD Group.
Some analysts attribute the growth in sales to an intrinsic change in the way activewear is designed. “Historically, what had been available to women were items based on a men's item that were just made smaller and turned a flattering color like pink,” said Scott Key, senior vice president and general manager of Athleta. “Women athletes expected more.”  Designers have recognized this "crossover" between exercise and fashion as a major opportunity for growth. It also syncs nicely with the overall trend in American fashion towards a more casual style of dress.