Wool is an animal-derived protein fibre with a layered internal structure and scales on its surface. Woolmark identifies keratin as its main structural protein and connects fibre diameter with the feel of finished textiles. Finer Merino fibres bend readily against the skin, while broader fibres serve different end uses.

A Wool Fibre Has a Layered Protein Structure

Understanding those features helps separate the raw fibre identity from a garment's construction. The same wool can enter a woven fabric, knitted garment or felted product. Fibre information explains the material source; the way those fibres become cloth explains a separate part of the textile.