Considering the basic form of a pair of sweatpants, it's really quite remarkable how many styles designers have managed to create, especially in recent years. A traditional pair of sweatpants, of course, is cotton and has elastic bands at the waist and ankles. Such pants are widely used among athletes, especially on high school athletic teams. They are also what many people turn to when they want to relax in their homes.

Sweatpants are baggy enough that they can be made to fit over another item of clothing, such as shorts. The layering possibilities contribute to the popularity of sweatpants among athletes, because the pants can be worn before, after and during competitions, at any time when the athlete is not working but still needs to maintain loose muscles. However, as mentioned, sweatpants have recently undergone a variety of transformations. Some of the new styles have evolved for purposes of functionality, but some are purely fashionable in nature.

About five years ago, women started sporting fashion tracksuits. These suits feature hooded, zip-up tops, or "hoodies," with matching sweatpants bottoms, and both pieces are usually made from velour. The important difference between these sweatpants and those traditionally worn by athletes is that fashion sweatpants lack the elastic band around the ankle. Instead, the legs are simply hemmed, rather like a pair of slacks. These suits were originally made popular by Juicy Couture, a trendy line of clothing for young women, but the sweatpants and tops were soon adopted by countless other labels, including Nike, Reebok, Adidas and other big names in sportswear. Although I personally find these suits rather ridiculous and often unflattering, they show no sign of lessening in popularity.

Windpants, on the other hand, serve a functional rather than fashionable purpose. Although some would consider these pants in a completely separate category from sweatpants, they are undeniably related. The telling factor is that both windpants and sweatpants serve, first and foremost, as cold weather protection for wearer. The difference with windpants is that instead of being made of cotton or some other easily permeable material, they are made of fabrics like polyester or nylon, which are (to some extent) windproof. Such pants often have zippers on the bottom of each leg, allowing the wearer to pull the garment without removing his or her shoes. Windpants may protect against the wind, but their fabrics lack insulation. Accordingly, these pants are often lined with cotton.

Tearaway pants are extremely popular in many sports. These garments feature metal snaps that run the entire length of both legs. The snaps are on the sides of the legs, allowing the wearer to essentially rip the pants off quickly and efficiently. Windpants are often also tearaway pants, as the characteristics of each are often valuable to athletes. Sports such as basketball and track, which often requires player to leap into play suddenly without a chance to warm up, favor tearaway pants. These garments are manufactured by all the large sportswear names, as well as many labels not traditionally associated with sports. Polo Ralph Lauren, Old Navy and Tommy Hilfiger all offer tearaway pants.