Early golf balls, such as the "featherie" and the "gutta percha," were made to be as smooth as possible in the belief that this reduced friction and drag and made the ball fly further.
As the game developed, it was discovered that this was not, in fact, true. A scuffed, rough ball surface actually led to better performance than a smooth one. This led to dimples being put into a ball's surface, the first appearing back in 1930. Modern balls typically have between 300 and 450 dimples. The governing bodies of the sport have avoided stipulating any maximum or minimum number. Instead, they just insist that the dimples are symmetrically placed over the whole surface of the ball.
Hit down on the ball to impart spin and help lift the ball into the air. The other main factors affecting how your golf ball performs during its flight are lift and drag. How you hit the ball can affect the spin imparted, but the other two factors are determined by the construction of the ball itself.
Strike the ball cleanly, and as it leaves the club and climbs into the air, it creates a high-pressure area in front of itself, where the air presses into it, and a low-pressure area behind. As the air passes around a spherical object, it creates a wake behind it. This is made up of turbulent air formed where the airflow has been separated as it passed the object. On a smooth ball, there is a wide area of turbulence, creating considerable drag.
Construct a golf ball with dimples that will create a thin layer of air that clings to the surface of the ball a fraction longer. This reduces the area of turbulence behind the ball and, therefore, the amount of drag. Studies show drag is reduced by up to 50 percent compared to a smooth ball, meaning the ball flies at least 30 percent further. The more dimples, the greater reduction in drag, up to a limit. Ball manufacturers are still researching what the optimal number of dimples is, leading to the current variety in both the number and shape of the dimples they put on the covers of their balls
Make the ball push the airwave it creates downward, and you will create lift. A dimpled surface on the ball increases this effect after the ball has been struck. The shape and depth of the dimples affect the flight. Dimples are 0.01 inches deep, and a variance of as little as 0.001 inches can affect the ball's performance.
Vary the shape of the dimples and you alter the ball's performance. Round dimples are currently standard, but recent studies have shown hexagonal dimples to be more effective in reducing drag. Callaway introduced a range of balls with hexagonal dimples in 2004 and other manufacturers are experimenting with different shapes at their research facilities.