bias binding

A "bias binding" or "bias tape" is a narrow, woven or knitted band. It's used in the clothing industry and tailoring to reinforce, conceal, or refine edges, especially on curved or angled cuts. Bias bindings can serve to hold layers of fabric together or give the garment a clean and professional finish.

Bias tapes are available in a variety of materials, widths, and designs, and can be both functional and decorative. In practice, the bias tape is often sewn so that it lies on the inside of the garment and is not visible on the outside, but it can also be used as a decorative element on the exterior.

For instance, in coats, a bias binding might be used to reinforce the inner side of the hem and achieve a clean finish. In certain garments, the bias tape might also be attached visibly on the outside as a design feature or to set a special accent.