To tackle is to physically interfere with the forward progress of a player in possession of the ball, such that his forward progress stopped and is not resumed, or that he is caused on touch any part of his body to the ground other than his feet or hands, or that he hurls the ball. So 150 pages for a 50,000 word book is about right. Tackles are important because they stop the game being played according to skill alone. If you want to stop someone like Paul Pogba or Luis Suarez from scoring goals or creating opportunities, then try to tackle them. It may not be easy, but if you get lucky and pull it off, then you have stopped them from scoring or creating something. There are two types of tackles: defensive and offensive. A defensive tackle's job is to prevent the ball-carrier from getting into open field by tackling him just short of the goalline or behind the line of scrimmage. An offensive tackle's job is to block defenders away from the ball-carrier while giving him room to run. There are also blindside and conventional tackles based on where on the field they are performed. A tackle is worth 2 points unless the player scores or advances the ball 1 yard or more (in which case it is 3 points). A tackle can also result in a penalty being assessed against the team who committed it.