The Explanation Of The Golf Swing Plan

I have been asked by a few players to explain what "swing plane" means and how the plane affects the results of the golf shot. So here it is:

An individual's plane is a line that is formed by the top of the shoulders and the ball. When you swing a golf club, the clubs position needs to be on, or slightly inside of this plane. When the club reaches a point that is parallel to the ground, the shaft line needs to be parallel to the target line (and thus inside the plane). The club is parallel to the ground at 5 points in the golf swing: once on the takeaway, once at the top of the back-swing, again on the forward-swing before impact, once after impact, and once when it reaches your forward shoulder. Check your swing and if it has these 5 parallel points, you are on plane.