The Set-Up is the static (non-moving) position in the swing just prior to the takeaway. The Set-Up determines how you move in your golf swing and is where you can make significant gains in your skill. If you have a swing fault in your Set-Up you will have a swing fault later in your swing. For example, a swing fault in your Posture will lead to another swing fault later in your swing with your Turn. The poor Turn leads to a mis-hit called Loss of Power.
What you need to know: Everyone can have a great Set-Up customized to match their best shot shape.