Moisture wicking describes a fabric's active transport of liquid sweat away from the skin to the outer surface where it can evaporate. Different from moisture regain (absorption): wicking relies on capillary action through the fibre structure. Synthetic microfibre fabrics (polyester, nylon) wick rapidly despite low absorption. Merino combines absorption and wicking. Wicking matters most in gym, sport, and hiking contexts where sweat rates are high.