The game of lacrosse is played using a combination of offensive and defensive strategies. Offensively, the objective of the game is to score by shooting the ball into an opponent's goal, using the lacrosse stick to catch, carry, and pass the ball. Defensively, the objective is to keep the opposing team from scoring and to dispossess them of the ball through the use of stick checking and body contact or positioning.
Settled offense: the 2-3-1
The most common offense used in settled situations is known as the "2-3-1" (sometimes counted in the opposite direction, as a 1-3-2, or shortened to be called the 1-3 or 13). The numbering begins with the two midfielders at the top of the field, then continues to the two attackmen on the wings and the midfielder on the crease, and finally the last attackman located at "X", the position behind the goal. The offensive team should pass the ball around the perimeter and look for weaknesses in the defense. They will also rotate, in two triangles. The midfielders will rotate in a triangle, across the top, and to and from the crease. The attackmen will rotate to and from X, and across the crease to the opposite wing. A player may "carry" the ball in a rotation as well; for example, a middle at the top right will carry to the top left, while the top left middle will cut to the crease, and the crease midfielder will cut into the space where the ball carrier came from.
Driving to the goal is aided by the triangle rotations, as it is difficult for the defense to keep track of the cutting players and the player who is attempting to drive to the goal. Some players prefer to drive from the midfield positions, as they do not have to turn to shoot, and they are often driving against a short stick defender. Other players prefer to drive from the wings and X, as it is often easier to pass to other players, who are more likely to be facing the goal for an easier shot.
Other settled offenses
There are other offenses which are commonly used. The second most common offense is probably the 1-4-1, where there is only one midfielder at the top of the field, two midfielders on the crease and two attackmen on the wings, and an attackmen at X. The formation somewhat resembles a cross. This offense is often considered better for driving, because it has a large amount of open space. The offense also allows the two players on the crease to attempt to set picks to get open, and screen the goalie on shots from the outside.
Another common offense is known as the "invert", and is more commonly used at the college level. This offense is structurally the same as a 2-3-1, but the midfielders and attackmen switch, or invert their positions. This is designed to allow midfielders to drive from the wings and from X against a short-stick midfielder, instead of against a longstick defensemen who would normally defend the player at these positions. It also allows attackmen to drive from the top of the field, where may they have a better chance of scoring, because they are facing the goal.
However, this offense can leave the team open to a fast-break, because when the ball is turned over, the midfielders are very far from their own defensive half. Some teams elect to send their attackmen back to their defensive half if there is a fast break, although this has the obvious disadvantage of forcing a primarily offensive player to play defense.
Another offense is the 1-3-2, which is somewhat similar to the 2-3-1 flipped upside down. In this offense, there is one midfielder at the top of the field, two midfielders on the wings and an attackmen on the crease, and two attackmen below the goal line. This offense is designed to allow the attackmen more opportunities to drive from below the goal, and allows the top midfielder a very open field to drive to the goal.