The top of pants or a skirt is finished with facing when

the raw edge of the waistline is enclosed between the outer fabric and facing fabric. This gives a clean and professional finish to the top of the garment. The facing is often cut from the same fabric as the main part of the garment or a lining fabric, and it is attached to the waistline using stitching. This technique helps in preventing fraying, provides stability to the waistline, and adds a neat appearance to the finished garment.