There are some slight variations between manufacturers, but the numbers of the clubs and their related earrings usually look like this. The number is related to the angle at which the face tilts backwards from the vertical when the club is held in its normal position in front of the ball. This is crucial when a golfer tries to send the ball over some obstacle, or when the golfer wants the ball to fall back at a steep angle, which tends to result in a shorter turn after landing. One of the other features you'll notice on the face of a golf club, the grooves, also help provide effects.
Like the tread of a car tire, the grooves on the club face give the water a place to go so that the ball does not slip across the face without spinning. First, they provide just a little bit of bite for the golf ball as it slides down the face, which helps it spin more quickly. A spinning golf ball is a good thing because the quick spin provides aerodynamic lift, which makes a spinning ball travel higher and farther than one without any spinning. A higher number for the club represents a greater degree of slope away from the vertical, which usually results in a higher and shorter shot.
In the woods, the wide, flat sole with rounded edges helps the head slide over the surface of the grass without digging. When you hear a host of a golf tournament talk about the player's selection of a club, you'll usually hear if the player has chosen a wood or an iron, and then a number. Finally, just before it leaves the club, the ball returns to its familiar shape and starts rolling down the face. According to the USGA, a ball hit by a wood or one of the longest irons (3 a) will spin at approximately 3,600 RPM when it leaves the club.