Mitten material can refer to two different materials, YARN and WOOL. YARN is a long continuous length of interlocked fibers, usually made of WOOL, cotton, or synthetic materials, which is used in the production of textiles, knitting, and crochet. WOOL is a type of animal fiber that is obtained from sheep and other animals, and is often used for clothing and other textile products. Both YARN and WOOL are commonly used to make mittens.