Overcast represents a sewing technique which involves making small in and out stitches to tightly join two material pieces together. This method adds strength and stops the material from fraying. The whipstitch can be used for a variety of stitching projects, like finishing the edge, sewing appliques, or even making quilts. It offers a neat and skilled look for the completed piece.

Whipstitch Definition Meaning MerriamWebster