Today's fabrics come from a variety of sources--different animals, plants, minerals or artificial processes--sources which can be grouped into two basic categories: natural and synthetic. Most of the time, we wear one, the other or a combination of both types of fabric without noticing the difference, but in certain situations, it's good to know your fabrics.
Natural clothes are clothes made of fabrics from material that occurs in nature: wools, hair, fur or silk from animals, or threads made from plants like cotton and hemp. Leather is also considered a natural fabric.
Synthetic clothes are clothes made from fabric that is the result of a chemical process. Synthetic polymers are woven into fibers which are then used to weave the synthetic cloth. Clothing made from these fabrics include nylon stockings and spandex shorts, as well as the iconic polyester leisure suit.
One of the major differences between the two types of clothing is how long the fabric lasts. Unless the natural clothing is treated with some kind of preservative, it will disintegrate and decompose over several years. On the other hand synthetic clothes tend to last longer. As an example, it takes nylon up to 40 years to decompose in a landfill.
Unless treated with flame retardant, synthetic clothes are relatively more flammable than natural clothes. Both types of clothes burn, and the rate of burn largely depends on the density of the material, but a synthetic material like acrylic, for instance, will burn faster than wool. Additionally, synthetic clothing may melt and meld to the wearer, causing more damage than the flames alone.
When considering factors like extreme weather or temperatures or athletic exertion, synthetic clothes have the advantage of materials that can be engineered specific to their purpose. Thus, popular waterproof, weatherproof clothing that is light, durable and dries fast tends to be made of some kind of synthetic fiber.
Natural fibers on the other hand, can vary in their effectiveness outdoors, although some of the higher end clothing can be just as, or even more effective than its synthetic counterparts.
It's a largely subjective notion, but natural fibers are often associated with better quality clothing and a more sophisticated style. The wool suit, for instance, is seen as a classic while the polyester suit is often seen as tacky. As style and fabrics evolve, with synthetics and synthetic blends coming closer to the look and feel of natural fabrics, the gap will likely narrow.