The designated home team takes to the field first, with the away team coming out to bat one at a time.
The pitcher has to pitch (throw) the ball to the batter while keeping one foot on the ground at all times. The pitcher's teammate, the catcher, crouches behind the batter.
A "strike" is called if the batter misses the ball and it is caught by the catcher; the ball goes through the strike zone without the batter attempting to hit the ball or; the batter hits the ball and its first bounce is outside the foul line. After three strikes, the batter is out.
If the batter hits the ball, and it is caught by a fielder without bouncing, he is out. Otherwise he can run to first base, so long as his ball is within the baselines. If he has hit the ball a long way, he can carry on to second or third bases, or even around the four bases and back to home plate to score a run.
A batter on one of the bases becomes a base runner, and the next batter takes his turn at bat. The aim of the base runner is eventually to run round all four bases to score a run. Only one base runner can occupy a base at one time.
If a batter hits the ball straight over the fence, this is called a home run, and the batter jogs round all four bases uncontested to score a run.
Base runners are safe on the bases, but can be dismissed by the fielders by being tagged - touched by a fielder holding the ball - or forced to leave his base by the arrival of another runner.
When both teams have completed nine innings, the team with most runs is the winner. In the event of a tie, extra innings are played until a winner is decided.