Lining and interlining are inner layers of fabric used in clothing construction. Lining provides a neat finish, conceals construction details, and extends the life of garments. It also adds warmth and allows clothing to slip on easily. Interlining is placed between the lining and outer fabric shell. It is used to maintain the shape and structure of garments. There are two main types of interlining - non-fusible which is sewn directly between fabrics, and fusible which is bonded using heat and pressure. Fusible interlining is most commonly used in apparel.