What is the purpose of interfacing in garment construction?

Interfacing is a textile material placed between the outer fabric and the facing (or lining) of a garment to add body, shape, and stability to specific areas. It is most commonly applied to collars, cuffs, waistbands, button plackets, and lapels, where the garment needs to hold a defined shape rather than drape loosely.

Interfacing comes in two main forms: fusible (iron-on) and sew-in. Fusible interfacing has an adhesive coating that bonds to the fabric when heat and pressure are applied. Sew-in interfacing is stitched into the garment and is preferred for delicate or heat-sensitive fabrics. Both types are available in different weights to match the garment fabric.

The correct answer is that interfacing is used to stabilize or support fabric. It does not finish seams (that is the role of seam finishes such as overlocking or binding), does not add decorative elements (that is the function of trims, embroidery, or applique), and does not create a lining (a lining is a separate layer of fabric that covers the garment's interior construction).

Exam tip: When asked about interfacing, focus on the concept of structural support and shape retention in specific garment areas.