Whilst the majority of golfers understand and experience the importance of hitting the ball out of the middle of the club (impact location), fewer are aware of low point.
If you imagine the swing as a big arc, the low point measures whether the lowest point of the arc is before or after the ball. It is another way of expressing "angle of attack", but I prefer it because it's easier to visualise.
Less established golfers have a misconception that the low point needs to be before the ball in order to help the ball in the air. But unless the ball is teed up, this can result in thins and fats.
Good ball strikers typically have a low point with irons 3-5" after the ball, ensuring a ball turf contact.
With driver, the ball can be teed up, and many long hitters make their low point before the ball, allowing an upward hit.
Consistency of low point is as importance as effectiveness. If for example your driver low point changes shot to shot, contact occurs at different moments in the clubface rotation, and thus compromises direction as well as distance.