Trick plays take advantage of defenses' expectations and conventional wisdom, the set of basic principles to which most offenses adhere. Most offenses follow a basic set of conventions in that once the ball is snapped to the quarterback, it seldom changes hands more than once: a hand-off or pitch to a running back, or a forward pass, and the players with the best skill sets for those particular plays are the ones that will execute them (for example, the quarterback is by far the best thrower on the field in most situations and would thus be relied upon for the vast majority of forward passes; likewise, kickers are, in the modern era, seldom relied upon for anything other than kicking). The typical American football playbook relies on simple, relatively low-risk plays with high odds of gaining yardage and low odds of catastrophe (a turnover, loss of yardage or, in the worst-case scenario, the other team scoring points). Trick plays eschew these principles: trick plays can easily exploit a defensive weakness if it is not foreseen, but if the trick is foreseen, it can be easily foiled, and the risk of catastrophe is much higher.