Dimples on golf balls help increase speed by reducing drag, the aerodynamic force that opposes a ball’s motion through the air. Their effect allows a struck ball to retain speed and travel much farther than a smooth sphere.
A golf ball is a blunt, roughly spherical object, so airflow separates from its surface and creates a large low-pressure wake behind it. The dimples create a thin turbulent boundary layer that stays attached to the ball longer. This delays flow separation, shrinks the wake, and substantially reduces pressure drag.
The dimples do not eliminate every form of resistance. They increase some skin-friction drag, but at typical golf-ball flight speeds the reduction in pressure drag is much greater. Backspin also interacts with the airflow to create lift, helping the ball remain airborne and increasing carry distance.
Golf balls were once smooth. Manufacturers and golfers eventually noticed that older, scarred balls often flew better, leading to deliberate surface patterns. William Taylor patented a dimple design in 1905. Modern balls commonly have roughly 300–500 dimples, with pattern and depth carefully tuned for speed, lift, spin, and control.