Curling Boundary Line Rules
Additionally, these lines also serve as a basis for where curlers are allowed to stand when their team and their opponent is shooting.
If any part of a stone crosses the sideline, it is considered to be out-of-play, and is removed immediately. Usually, this does not happen when a stone is being shot, but could occur. This may happen if another stone is thrown and hits the stone at rest, causing it to reach one of the sidelines.
If a stone fully crosses the backline, it is considered to be out-of-play, and is removed immediately. The stone is in-play as long as any part of it remains in front of the backline, even if it is just a tiny sliver of the stone.
After a stone is delivered, it must fully cross the farther hog line to be considered in-play. Even if a tiny sliver of it is in front of the hog line, the stone must be removed from play.
There is one exception to this rule. If a stone runs into another stone and cannot fully cross the hog line, it is allowed to remain in-play. This is because if the other stone wasn't there, the thrown stone would have crossed the hog line, and would be in-play.
Just like the stones, curlers have certain places they should stand when their team is and isn't shooting.
When a team is shooting a stone, there is one player in the house (called the skip), and is calling the shot that needs to be made. Then, there is one thrower that is crouched in the hack, and is ready to deliver the stone.
Finally, there are two sweepers that typically stand in between the hack and the hog line. This allows them to walk with the stone during the entire shot, and so that they may sweep when necessary.
While the shot is being made, the sweepers will continue to walk with the stone. The thrower may decide to follow the sweepers behind the stone, or may stand by the hog line where they released the stone. The skip will usually remain in the house, but may help the sweepers on occasion.