When you are teeing off or hitting the ball from the fairway, it's important to have your front shoulder facing the target so you are aligned squarely. Your front foot is beneath your front shoulder to give you a chance to hit the ball with power and accuracy. But at times you may need to open your stance to get the ball to fly at the flagstick or stay away from a troublesome spot on the course.
An open stance turns a right-handed golfer's body to the left of the target. It encourages your arms to swing left and helps produce a slice or a fade. If you are teeing off on a hole that is a straight shot to the green, you want to avoid this. But if you are in the left rough and the hole is on the right side of the fairway, you want to hit a ball that goes left to right to help the ball get to the green. This is one of the main reasons to play an open stance.
Playing an open stance is the way to go when hitting the ball from the bunker. An open stance will create extra spin on the ball when you swing your wedge. Since you are hitting the sand behind the ball and not the ball itself, the extra spin will help get the ball over the lip of the bunker. If you can land your ball to the left side of the flagstick, it will tend to roll to the right after it hits the green.
When you want to hit a left-to-right fade from the fairway or the short rough, take a slightly open stance and use your normal swing. The ball will go from left to right and give your shot a chance to get to the green. Opening your stance when you take a chip shot will encourage you to get a clean follow-through that will enable the ball to get to the green when chipping from 50 to 80 yards away. If you are pitching the ball from a short distance and using a gap or lob wedge, a high finish is essential. Opening your stance will help you get the high finish that allows you to stop the ball with backspin.
Opening your stance will give you a better view of the target. When you are 150 yards or less from the hole, you are looking for touch and accuracy. You are not trying to add extra power. To get that extra bit of feel and touch, open your stance to have a better view of the shot you plan to execute.
While opening your stance can help when you have a shot that requires left-to-right movement, you do not want to fall in the bad habit of opening your stance on all shots. Most tee and fairway shots require you to be square to the target. If you open your stance too frequently, you will find yourself slicing the ball and playing from the rough or the hazard on most of your shots.