Most modern sewing machines have a reverse button and you can sew in reverse as you press this. You can use this with a straight or zig-zag stitch and your machine will sew that stitch backward. A reverse stitch is mostly used as an Anchor stitch
When you start to sew you are eager to get on with your sewing but taking a simple precaution at the start of the sewing will ensure that you will not have unraveling seams – I am talking about making securing lock stitches at the start and end of stitching.
To make this stitch, straight stitch about 3 stitches forward and then change the lever to reverse stitching and go back the same way 3 stitches. Come back and then continue your sewing. This is how you secure the stitches. Do the same when you end your stitching.
Another method is to reduce the stitch length to 0 and sew three stitches in the same place. With a zig-zag stitch you will use straight stitches as anchoring stitches.