when does a runner have to be tagged in baseball
Tag out A batter can also advance to the next base because he chooses to. For example, suppose, with a runner on first, the batter hits a groundball single into the outfield. As the batter runs to first, the runner on first is forced to advance ahead of him to second. However, that runner can then choose to run past second and on to third. In this situation, a defensive play against such an unforced runner will be called a tag play and, if successful, a tag out. To get the runner out on a tag play, the fielder must tag him with the ball before the runner gets to the targeted base. Tag plays are much more difficult to execute than force plays.[2]
Baseball field The lines from home plate to first and third bases extend to the nearest fence, stand or other obstruction and are called the foul lines. The portion of the playing field between (and including) the foul lines is fair territory; the rest is "foul territory." The area in the vicinity of the square formed by the bases is called the infield; fair territory outside the infield is known as the outfield. Most baseball fields are enclosed with a fence that marks the outer edge of the outfield. The fence is usually set at a distance ranging from 300 to 420 feet (91 to 128Â m) from home plate. Most professional and college baseball fields have a right and left foul pole. These poles are at the intersection of the foul lines and the respective ends of the outfield fence and, unless otherwise specified within the ground rules, lie in fair territory. Thus, a batted ball that passes over the outfield wall in flight and touches the foul pole is a fair ball and the batter is awarded a home run.