Bluff catching range

This is the number of hands that don't have any real value left on the showdown, but might still be good enough to catch the bluff of an opponent, i.e. you beat his bluff.

Example: You put your opponent on a flush draw on the flop, but it hasn't arrived by the river. You don't have a made hand and assume that your opponent will bluff the river with his busted flush draw every now and then. You need to ask yourself how often and with what range he will do so and accordingly choose the range with which you can catch a bluff.