Fusible interlining is a type of fabric used in garment construction to provide structure and support. It is typically made from a blend of fibers and has a heat-activated adhesive on one side. When pressed with an iron, the adhesive bonds the interlining to the main fabric, enhancing its durability and shape. This material is commonly used in areas like collars, cuffs, and waistbands, where added stiffness is desired. Fusible interlining comes in various weights and types, allowing designers to choose the right option for their specific fabric and garment needs.