Self-fabric is a term used in sewing. It refers to a fabric piece or embellishment made from the same fabric as the main fabric, as opposed to contrast fabric.
Self-fabric is usually used in certain pattern pieces such as facings and linings to produce clean garment lines and make the fabric piece blend in with the rest of the garment. A special type of button is often covered in self-fabric to minimize its visibility.
Self-fabric can also be used to make design details stand out. For example, a patch pocket on a coat could be made of contrasting fabric, but have an appliqué made of self-fabric on the pocket. A very common use of self-fabric as an embellishment is to make two garments that are to be worn together out of different fabrics and use self-fabric from one garment as a trim on the other (such as piping).