One of the first things any beginning golfer should learn is the difference between various clubs. At the most basic level, there are two main types. Those with smaller, thinner heads made from steel are called irons. The big-headed clubs, usually made of titanium or steel and coated with paint, are called woods. (That’s what they used to be made of.)
Irons are normally used from fairways, rough, from the tee of a short par 3 or when trying to avoid trouble such as a hazard. Iron shots typically don't go as far as wood shots, but are easier to hit accurately. In fact, some players choose to exclusively hit irons, sacrificing distance for accuracy.
The woods generally feature longer shafts and less-lofted clubfaces; therefore, they hit the ball farther but are harder to control than irons. Woods are normally used off the tee box for maximum distance, but can also be used from the fairway or rough when you have a long way to go to reach the green.
The driver, or 1-wood, is usually only hit from the tee, because it’s extremely difficult to hit off the ground. Be careful not to default to hitting a wood from every tee, though. Sometimes you'll want to use a shorter wood, an iron or a hybrid club – a combination wood/iron -- to avoid trouble such as a hazard.
Hybrids have features of both a wood and iron. They are easier to hit than a lot of woods and irons and offer more distance than irons. Because of this, hybrids are useful from both the tee and fairway.