In each game of field hockey there are two umpires or referees. The middle of the field can be controlled by either umpire, but each of them get to control their own side of the field. If the umpire gives you a green card it means that the player has gotten a warning and they have to stop what they are doing. If you get a yellow card it means that you are suspended temporarily for at least five minutes of playing time. The worst card you can get is a red card, that means permanently suspended from the match. If you are suspended from the game then your team has to play with fewer players than the opposing team. The umpires favorite thing to do is to blow their whistle. They blow the whistle to: start a bully and end a penalty stroke, re-start a match or to stop the match due to injury. They mostly use the whistle to start the first/ second half of the game, to call a foul or to indicate a goal. The umpire is the person who keeps the game moving smoothly.