The worldwide postal system constituting the individual national postal systems of the world's self-governing states is coordinated by the Universal Postal Union, which among other things sets international postage rates, defines standards for postage stamps and operates the system of international reply coupons.
the worldwide postal system constituting the individual national postal systems of the world's self-governing states is coordinated by the universal postal union which among other things sets international postage rates defines standards for postage stamps and operates the system of international reply coupons