An embroidery digitizing zigzag stitch alternates from one side to the other in an angled fashion. Zigzag stitches are used primarily for underlay; however they are the stitch of choice for securing applique.
Embroidery Zigzag is well suited as an underlay for satin stitches, because the stitches are always at an angle, which prevents them from popping through the top stitch. A variation is called double zigzag, which alternates back up the column on the opposite side as the initial zigzag stitch.