Fleece is a synthetic material made from polyester. The raw materials for polyester are made from two petroleum products: terephthalic acid and ethylene glycol. However, polyester can also be made from recycled plastic such as PET soda bottles.
A characteristic of many man-made fabrics such as fleece is the ability to resist moisture and withstand “wear and tear.” Fleece is warm like wool, thick and deep-pile. It also dries quickly. Unlike wool and other fabrics that begin to accumulate little “woolly” balls on the fabric as it begins to age, fleece does not do this. Fleece already has a “woolly” look and feel on both sides, but it does not bunch up or thin after extended use.
Fleece is often preferred because of its man-made characteristics. For instance, it is often used in outdoor gear because it has the ability to keep its wearer warm and dry. Because it resists moisture, fleece will only absorb a small percentage of moisture if it gets wet. Also, the sections of the fleece that do absorb moisture will dry quickly, which makes fleece a perfect material for cold and wet climate activities. According to Made How, hikers are partially responsible for the popularity of fleece in outdoor gear because they found fleece to be warmer and more lightweight than wool.