Interlining is a technique used in the textile industry to add structure and support to garments. It involves placing a layer of fabric, known as interlining, between the outer fabric and the lining. This additional layer can enhance the durability, shape, and overall appearance of clothing items like jackets and coats. There are different types of interlining, including fusible and sew-in options. Fusible interlining has an adhesive backing that bonds to the outer fabric when heat is applied, while sew-in interlining is stitched in place. Both types help improve the garment's fit and longevity.