What is the purpose of using interfacing in sewing?

The purpose of using interfacing in sewing is primarily to add structure to the fabric. Interfacing is a material that is applied to the wrong side of a fabric to enhance its durability, stiffness, or shape retention. This is especially important in areas like collars, cuffs, waistbands, and button plackets, where additional support is necessary to maintain a well-formed and tailored appearance. By incorporating interfacing, garments not only look more polished but also perform better over time, resisting wear and maintaining their intended shape.

While interfacing can indeed contribute texture and sometimes even influence the weight of a garment, its main function is to provide that structural support which ensures garments hold their form throughout use and wear.