Irons

Irons are so-called because their club heads are made of metal. Of course, "woods" are now also made of metal, but that's a relatively recent development. Irons have featured metal club heads (steel, these days) for centuries.

Irons feature thin club heads and grooved faces. Accomplished players might choose a "muscle back" or "blade" style of iron, whereas beginners and most recreational players will want a "cavity back" style.

The difference is that a blade-style features a full back on the rear of the club head, whereas a cavity back is exactly that: the rear of the club head is, to a certain degree, hollowed out. This creates an effect known as "perimeter weighting," which is helpful to less-accomplished players. A typical, off-the-shelf set of irons will include a 3-iron through pitching wedge (advertised as "3-PW"), 8 clubs total.