The teeing area is where you start each hole and is one of the five defined areas of the course. It has a defined size and shape that is a two club-length deep rectangle measured from the tee-markers you are playing your round from.
You can stand outside the teeing area as long so your ball is within the teeing area. Before you play, you are not allowed to move the tee-markers. When playing from the teeing area, you can tee your ball or play it from the ground, use a borrowed or abandoned tee (even if it is broken), and re-tee your ball if it falls off the tee before you play it.
If you play a stroke from outside the teeing area, the Rules are different depending on whether you are playing match play or stroke play. In match play, your opponent has the option to cancel your stroke. If they do so, you need to play again from within the teeing area without penalty. If your opponent doesn’t cancel your stroke, you will continue to play with the ball you played from outside the teeing area (also without penalty). In stroke play, you are required to correct the mistake by playing again from inside the teeing area, and in this case, you will get a two-stroke penalty.