When a ball lands on the line in most sports, it is considered "in" or good. Specifically:
- In tennis, any part of the ball touching the line means the ball is good, even if most of it is outside the line. A player should only call a ball out if they clearly see space between the ball and the line
- In soccer, the lines are part of the playing field, so if the ball touches the line, it is still in play. The ball must completely cross the boundary line to be out
- In pickleball, any ball that touches any part of a line is considered in during rallies, including sidelines and baselines. However, on serves, if the ball touches the non-volley (kitchen) line, it is out
- In volleyball, if the ball lands on the boundary line, it is considered in play. If it lands outside the line, it is out and the point goes to the opposing team
- In general, the rule is consistent that the ball must be completely outside the line to be considered out. Even if a small part of the ball touches the line, it is in
Thus, the common principle across many sports is that the line is part of the playing area, and a ball landing on the line is considered in.
