In lacrosse, you can be in one or more out of four positions. The four positions are mid-fielder, attack-man, defense-man, or goalie. Mid-fielders run up and down the field usually carrying the ball. If not, they are chasing the ball. The attack-men stay in the opposing goal area to wait for a pass. The defense-men stay in their teams goal area, to attemp to stop mid-fielders and attack-men from scoring. The goalie is the last defense. His job is to block the ball from going into the net.
There are several rules to lacrosse, but I won't get into that.