The driver (designated as a 1-wood) is most commonly used for tee shots on par-4s and par-5s, with the ball teed up. Some highly skilled golfers may rarely attempt to play a driver from the fairway, but most golfers should stick to using driver only off a tee.
Because the driver is the longest-shafted club and has a low amount of loft, it is often the club most difficult to use for amateurs and recreational golfers.
"Driver" can also be used to refer to a golfer, as in, "Jack Nicklaus was a great driver of the golf ball." In this usage, "driver" is referring to a golfer's proficiency in using the club.