Where the ball sits relative to a golfer's stance, front-to-back — the simplest setup variable, and the one that most directly controls low point and launch angle.

The driver is played farthest forward, just inside the lead heel, so the club is already moving upward at contact for a high, low-spin launch off the tee. Wedges sit in the center of the stance, putting the swing's low point just after the ball for a descending, ball-then-turf strike. Mid-irons fall in between. Moving the ball back in the stance without changing anything else steepens attack angle and lowers launch; moving it forward flattens attack angle and adds launch — which is why a single ball creeping an inch forward or back is a common, invisible cause of thin or fat contact.