Golf is played with golf clubs of various types. There are four major categories of clubs, known as woods, hybrids, irons, and putters. Wedges resemble irons and may also be counted among these. A golfer is allowed to carry up to fourteen clubs during a round.
While it is possible to play a range of different shots using only one club, modifying only the speed and direction of swing, this is not a particularly successful technique. It is much easier to keep the swing as constant as possible and achieve different lengths and characteristics of ball flight using a different club for each shot. To facilitate the choice of a club for any particular situation, all irons (and many woods and wedges) come in sets of similar clubs graded by loft (see below), shaft length, and weight. Clubs are numbered for identification with the smallest numbers indicating the lower lofts (a 5 iron has less loft than a 6 iron).
Various clubs are designed with the face having differing loft (the angle between a vertical plane and the clubface when the club is at rest). It is loft that makes a golf ball leave the ground on an ascending trajectory, not an upward direction of swing: with the exception of the tee shot, the club actually hits the ball in a horizontal or slightly downward motion. The impact of the clubface compresses the ball. Grooves on the clubface impart a counterclockwise (from a parallel view of the swing) spin, known as backspin, on the ball, that when combined with the rebounding effect of the ball, give it lift. Typically, the greater the loft, the higher and shorter the resulting ball trajectory.
A typical set of clubs generally consisted of 3 woods, 2 wedges, a putter, and 8 irons, numbered 3-9, and a pitching wedge. This has changed greatly in the last 25 years, as most players have opted to take 2, or even as many as 5, of the difficult-to-hit longer irons out of the bag in favor of higher lofted woods, known as fairway woods, and extra "utility" wedges. In part, this reflected a redesign of clubs in which manufacturers reduced the lofts of the irons to make them appear to hit longer. In effect, today's 3 iron has a loft that is equivalent to a 2 iron of years ago.