Which fiber is known for being soft, white, downy and durable, commonly used in underwear and socks?

The fiber that is recognized for its softness, white, downy texture, and durability, particularly when used in items like underwear and socks, is cotton. Cotton fibers are breathable and have a comfortable feel against the skin, making them ideal for undergarments and everyday wear. They are naturally absorbent, which adds to the comfort factor, and they retain their shape and integrity even after repeated laundering, contributing to their durability. Cotton's versatility and availability have made it a staple in clothing manufacturing, particularly in garments that require a soft touch and good moisture management.

In contrast, wool, while also soft and durable, is not typically used for items like underwear and socks designed for warm weather due to its insulating properties. Silk provides luxurious softness and a smooth texture but lacks the durability for everyday use in the same capacity as cotton. Linen, known for its breathability and strength, is not downy and soft like cotton, making it less suited for intimate apparel. This context highlights why cotton is the preferred choice for the items in question.