Appliqué is the technique of cutting out small pieces of fabric (‘slips’) and attaching them to a larger piece of fabric. The term comes from the French verb to apply.
The slips are stitched around the edges with either slip stitch (where the edges have been folded under to form a hem) or stab stitch (where the edges have been cut). This stitching holds the slips in place and can be covered by other more decorative stitches.
Appliqué works from the medieval period still exist, although the technique is almost certainly considerably older. Appliqué is also used in stumpwork and some whitework techniques: needlelace slips are worked and then applied to a ground fabric.