Tacks are mainly used to secure the ends of pockets and pleats where added reinforcement are needed. When done correctly they are also an attractive feature.
An arrowhead tack is created by marking the size of the triangle in the appropriate place with a tailor’s chalk. Begin by inserting the needle from the wrong side, into the bottom left corner. Then take a stitch from right to left through the top point, then down into the right corner and coming out at the starting point in the left corner. Repeat the process until the area is filled with stitches.