In knitting, bining off, or casting off, is a family of techniques for ending a column (a wale) of stitches. Binding off is typically used to define the final (usually upper, taking the cast on edge as the lower) edge of a knitted fabric, although it may also be used in other contexts, e.g., in making button holes. In principle, binding off is the opposite of casting on, but the techniques are generally not mirror images of one another. Sometimes, however, they can produce a mirror image appearance.