Spandex is a synthetic fabric with a polymer base, like nylon or polyester; spandex, however, has unique properties that make it well suited to certain applications, such as sports apparel. The fabric is able to expand up to 600% and spring back without losing its integrity, although over time, the fibers may become exhausted. Unlike many other synthetic fabrics, spandex is a polyurethane, and it is this fact that is responsible for the fabric's peculiarly elastic qualities.

Spandex is a synthetic fabric with a plastic base. Some people are allergic to it, while other people refuse to buy synthetic fabrics for the well-being of the planet or because they believe natural fabrics wear or wash better. When people are allergic to spandex, their skin is usually irritated when they come in contact with it. While spandex is more prevalent in women’s clothing, a spandex allergy can be frustrating for both sexes because underwear for men and women often has at least some spandex in the elastic band. On the other hand, people who do not buy synthetic fabrics generally don't because they consider themselves green, because natural fabrics wear better, or both.

Spandex was developed by Dupont® in 1959, long after many other synthetic fibers were developed by the same company. Formerly, foundation garments and compression garments were made with rubber, which was expensive, difficult to manipulate, and often irritating to the skin. Spandex replaced rubber in most of these applications, allowing people to wear garments that would adjust to their shapes but still breathe, so that sweat and dirt didn't accumulate next to the skin. The sporting goods industry quickly picked up on the new fabric as well, seeing a potential for a flexible, breathing fabric. One company who has become one of the most well-known brands of spandex is Lycra®, which is very popular with athletes.

When choosing spandex garments there are few things you need to keep in mind. First is the purpose of the garment. For example, if you are looking for a pair of running pants then you need to decide between the tight and loose variety. The tight ones are great for cold days and short runs as they keep you warm while the more baggy variety is great for warm and mild days.