Elastic yarns are produced with core as continuous elastomeric yarns and sheath as continuous multi filament yarn or staple fibres. Elastic yarns have unique properties. They have the same feel as the shield fibers because the shield performance fibers cover the outer layer. They are comfortable to wear and can modify their elasticity to fit different end-products. Elastic yarns can be used to produce fabrics of varying styles, hands and functions, and can be designed for woven and knitted fabrics according to their properties. Swimwear, active wear, circular knit fabrics and narrow fabrics are the common applications for elastic yarns. Elastic yarns are also used for stretched woven fabrics and suitable for casual wears, jeans corduroy, and evening gown, outwears and bottom wears. The textile industry has produced more indigo denim than any other woven fabric. The reasons for the unmatched success of denim are durability, comfort, feel, appearance and versatility. Now, denim trends are modified according to customer's requirements to improve the quality of the fabric. Stretchable denims are more popular than regular denim, because of their elasticity and fit.