Whipped Back Stitch:
1. Embroider a shape using the back stitch.
2. Pull out the threaded needle through the upper corner of first back stitch from any of the sides.
3. Pass the thread over the back stitch.
4. Insert it through the the lower corner of the first stitch without plucking the fabric or the next stitch.
5. Pass the needle over the second back stitch and insert through the lower corner just like the previous one.
6. Continue the process.
The Picture Guide: