The position of the ball varies depending on the selection of the club.
Short irons: These include the 9-iron, the 8-iron and the wedges. For these irons, the ball must be positioned in the center of the stance. The clubs are placed almost straight and the golfer needs to swing at a steep angle, taking a divot after hitting the ball.
Middle iron: The 7-iron, 6-iron and 5-iron fall in this category. The ball is placed closer to the front foot from the center. The irons are placed at a much flatter angle and the club should strike the ball at the bottom of the swing arc.
Long iron: These include the 3-iron, 4-iron and fairway woods. Here the ball is placed two balls closer to the center of the front foot. In this position the ball has to be struck at the bottom of the swing arc.