Balance points

Balance points are points (marked by notches) on your pattern that help you put the right pattern pieces together (they can indicate front and back, or which way is up or down).

If you mark balance points at regular intervals, they can also help you when you are sewing a very long seam, or a curved seam. For example, I tend to always add a balance point (or two - depending on the length of the seam) part way down my side seams to ensure that the pieces are sewn together perfectly and I do not accidentally stretch one of the layers of fabric (which will leave me with excess fabric at the end of the seam).