If a fabric is moisture-wicking, it means it will 1) transport sweat away from your skin into the top layer 2) dry out quickly to prevent sweat from soaking the fabric. Moisture-wicking performance is predicted by the capillary action—the movement of liquid through spaces in the fabric. The most effective moisture-wicking fabrics are synthetic fabrics such as polyester, nylon or microfiber (often a polyester-nylon blend). These fabrics are “hydrophobic”, meaning they resist water penetration.