Every golfer is a bit different in size, body shape and the shape of their golf swing. A custom fitting results in clubs that are specifically suited to an individual's height, strength, clubhead speed and swing characteristics.
Off-the-shelf golf clubs are one-size-fits-all, designed for the "typical" golfer. In this case, typical means someone 5-foot-9 or 5-10 who hits a 5- or 6-iron 160 yards. A golfer might get lucky with an off-the-shelf set, but many golfers will find themselves ill-suited to such a set.
And the adjustments a golfer makes in his or her game to compensate for an ill-fitting set can make grooving a great swing that much more difficult.
A clubfitting can be performed by nearly any pro shop or golf pro, although it's best to get with a teaching pro and be certain to hit balls outdoors so that the ball flight can be observed.
Contrary to the belief of many, clubfitting does not have to be a time-consuming or expensive endeavor. A very basic clubfitting might take as little as 15 minutes, with the average being 30-45 minutes.
More in-depth fittings can take a half day, but are only likely to be necessary for the very best players.
As for price, some clubs will give you a fitting free of charge as long as you agree to purchase your new set from them. Most charge a modest fee, perhaps $35 to $50 being typical.
During the fitting, the golfer hits many variations of the same club. For instance, a well-equipped fitting center might have dozens (in some cases, hundreds) of a particular club, say a Ping 6-iron. Each of the Ping 6-irons will be different from the next in some way.
The idea is to find the best combination of shaft (length, flex and kickpoint), loft (standard, strong or flat), lie (strong or flat), grip and swingweight, among other factors.
By watching the ball flight produced by each variation of a club, and checking chalk marks left on adhesive strips attached to the clubface and sole, a clubfitter can quickly narrow the search and lead the student to the best fit.
Fittings can be done for every club in the bag, including putters, but iron fittings are most common, with driver fittings following closely behind.
Of course, a fitting only works if you follow up by purchasing a set of clubs custom made to those specifications. Two things to keep in mind: If you want a set of, for example, Titleist clubs, the ones you order after a clubfitting will cost approximately the same as the same set bought off the shelf; and a golfer is under no obligation to purchase a set from the pro doing the fitting.
So there's little reason for anyone in the market for new clubs to avoid a clubfitting.

