In the simplest lawn bowls game, singles, one of the two opponents begins a segment of the competition (in bowling parlance, an “end”), by placing the mat and rolling the jack to the other end of the green as a target. Once it has come to rest, the players take turns to roll their lawn bowls from the mat towards the jack and thereby build up the “head”.
Lawn bowls reaching the ditch are dead and removed from play, except in the event when one has “touched” the jack on its way. “Touchers” are marked with chalk and remain alive in play even though they are in the ditch. Similarly if the jack is knocked into the ditch it is still alive unless it is out of bounds to the side resulting in a “dead end” which is replayed.
After each competitor has delivered all of their lawn bowls (four each in singles), the distance of the closest lawn bowls to the jack is determined (the jack may have been displaced) and points are awarded for each lawn bowl which a competitor has closer than the opponent’s nearest to the jack. For instance, if a competitor has bowled two lawn bowls closer to the jack than their competitor’s nearest, they are awarded two points. The exercise is then repeated for the next end.
Particularly in Lawn Bowls team competition there can be a large number of lawn bowls on the green towards the conclusion of the end, and this gives rise to complex tactics. Teams “holding shot” with the closest lawn bowl will often make their subsequent shots not with the goal of placing the lawn bowl near the jack, but in positions to make it difficult for opponents to get their lawn bowls into the head, or to places where the jack might be deflected to if the opponent attempts to disturb the head.
Not for the faint-of-heart, here are the official World Bowls Laws of Lawn Bowling (in pdf format):