The number of defensive penalties accumulated during a game is counted in this statistic. It is sometimes used to track the total number of yards lost due to defensive penalties. It is usually tracked on a per game and a per season basis in order to gauge how well the defense plays.
A team with a large number of defensive penalties will have a hard time winning many games. Almost every single defensive penalty will result in gained yardage for the offense. Sometimes it even results in an automatic first down. A pass interference penalty called on a defensive back could take the offense from their end of the field down to the goal line. For these reasons and more, defensive coaches and players do everything they can to ensure they are not penalized. Holding is a fairly common occurrence during the game, and is one of the most common penalties. When called often, it indicates a player is getting beat by the opposition and is therefore not playing their position as well as it could be.