Coral stitch is also known as knotted stitch, snail trail, beaded stitch or German Knot.
Coral Stitch is used in White work Embroidery as a reinforcement stitch along with the Chain stitch. It is also used in surface embroidery to create continuous knots. It can be used for outlining a design on even for filling an area when worked parallel and close to each other.
Bring the needle up at 'a'.
Place the working thread along the line of the design.
Pass needle into the fabric under the embroidery thread picking 2-3 thread from 'b' to 'c' .
Pull the needle while the embroidery thread is looped under the needle (shown above).
How to work Coral Stitch at the Corners
Finish the last coral stitch at the corner.
Take the needle to the other line passing the needle into the fabric and bring it up where next stitch has to be placed as shown in the picture above.
Continue working the stitch.
Happy Stitching !