American Football is similar in many ways to both codes of rugby (and in fact was developed as an offshoot of rugby). It is probably more like rugby league in that each team only gets a limited amount of chances to advance the ball forward at which point they must handover possession. In Rugby League this happens after six tackles are completed, whereas in American Football it occurs when the attacking team fail to advance the ball forward by ten yards over a series of four plays (excluding penalties as will be explained shortly). In Rugby Union, on the other hand, the attacking team can go through as many phases of possession as they wish (as long as they do not commit an offence).