Teams use certain strategies within a game depending on who the opponent is that they are playing. Strategies are often developed and built open during practices throughout the course of a week leading up to gamedays. Strategies help a team feel prepared and in sync on the ice at all times. Players are more likely to be where they are supposed to be and will know where their fellow teammates are positioned as well.
Defensive minded teams often like to sit back in a 1-3-1 or 1-2-2 formation. This means that they only send 1 forward to forecheck (apply pressure on the opposing team), while having the other forwards and defenders sit back in the neutral zone. Teams will often use this strategy if they are winning a game in order to prevent a team from scoring.
Offensive minded teams often run a 2-1-2 or 2-2-1 strategy. This means they send 2 forwards on the forecheck while having another forward and/or defenseman hanging by the blue line just in case there is a loose puck. Teams will often use this strategy if they are losing a game and in need of a goal.