When you hear a softball fan describing a play, she might use numbers between one and 10 to refer to the defensive players. These numbers aren't tied to the numbers on the players' jerseys -- they're a numbering system typically used to keep score during the game. Every position on the field has an assigned number.The pitcher and catcher form the battery in softball. The pitcher is No. 1 and the catcher is No. 2. If the bases are loaded, the batter hits a ground ball back to the pitcher and she throws it to the catcher for a force play at home, the scorekeeper writes down "1-2" in the scorebook to indicate that the pitcher fielded the ground ball and the catcher recorded the out.A defense in softball includes four infielders. The first baseman is No. 3. The second baseman goes by No. 4. The third baseman is No. 5 and the shortstop is No. 6. If the batter hits a ground ball to the shortstop and she throws the ball to first base, the scorer writes down "6-3" in the scorebook if the throw beats the runner for an out. If a runner is on first base and a ground ball is hit to the third baseman, she would throw to second base to get the lead runner and the second baseman throws to first to try to get the double play. If that play was successful, the scorer writes down "5-4-3" in the scorebook.The traditional outfielders in softball play left field, center field and right field. The left fielder is designated by the No. 7, the center fielder is No. 8 and the right fielder is No. 9. If the batter hits a fly ball to the center fielder and she catches it, the scorekeeper would write down "8" in the scorebook to designate that the center fielder caught the fly ball and an out was recorded without the assistance of another player on defense.The extra fielder in softball normally plays in the outfield. That position is designated by the No. 10. In most cases, the coach will position four outfielders across when playing defense in softball. In some cases, the extra fielder will play in short center field while the traditional center fielder plays much deeper. The coach can position the extra fielder anywhere on the field. The rules of the game of softball state that all defensive players other than the catcher must be in fair territory, which gives the coach the right to position the extra fielder anywhere she chooses.