Lines, goals, set ball
The whole ball must be past the line to be out. If any part of it is still on the line, it is still in.
The same applies on the ground and in the air.
It is also out if it stays wedged between opponents for more than 5 seconds.
And out if it rises more than 50.8cm off the floor and the referee judges that dangerous. If the referee does not, play continues.
When the ball goes out, play restarts with a kick-in, a goal kick or a corner kick — depending on which line it crossed and who touched it last. See the [Restarts] card.
A goal follows the same principle: the whole ball must roll fully over the goal line between the posts.
The restart used when play is stopped for a reason the Laws do not name elsewhere. A ball bursting in play is one example.
The referee places the ball where play stopped. One player from each team takes position within 30cm of it, each the same distance away, both facing the ball. Everyone else stays 3m back.
Play restarts on the referee’s signal.