Just as a stiff club plays differently than a flexible club, so can the compression of a golf ball result in a different play. Understanding the different compressions of golf balls can help you select the one which will best suit your game.
The compression of a golf ball refers to how tightly wound its core threads are. The tighter they are wound, the harder or more compressed the core is. Golf balls come in a variety of compression rates (most commonly 80 to 100), with the lower number representing lower compression. A ball with a low compression is wound less tight and is considered softer. A ball with a higher compression is wound tighter and is referred to as being harder.
Low compression balls (80 or below rating) travel farther than more tightly wound balls due to their softness and the reaction they have to a swung club (more rebound off the club). Think of a gymnast bouncing on a trampoline or on cement--the soft trampoline provides more rebound and sends the gymnast higher. Due to their softer characteristic, low compression balls will not fly as straight as harder balls, and will be harder to control.
Medium compression balls have a rating of 90 and provide the best combination of distance and control.
High compression balls have a rating of 100 or higher, and are used by the hardest hitters, who may often need the maximal accuracy they provide.
Since lower compression balls provide more distance, players with slower swing speeds (generally beginners, juniors, seniors and women) prefer these types of ball. Medium compression balls are preferred by most advanced players who can generate superior (but not necessarily maximal) club speed, and who want optimal control to go with their power or distance. Higher compression balls require a faster swing speed to achieve maximal distance, but provide a truer flight, and are therefore preferred by more power hitters.