Fusible interfacing is a type of fabric used in sewing to provide extra support and structure to garments and other textile projects. It is typically made from a blend of fibers and has an adhesive coating on one side. When heated with an iron, the adhesive melts and bonds the interfacing to the fabric, making it easier to create crisp edges and maintain the shape of the finished item. This material is commonly used in areas like collars, cuffs, and waistbands, where added stiffness is desired. Fusible interfacing comes in various weights and types, allowing sewists to choose the right option for their specific project needs.