Think of a coupon for a free pizza that you receive in the mail. The coupon was created before the pizza was made and the pizza company did not have to have any pizza ready before it printed the coupon and mailed it to you. The pizza will be made only if you present the coupon at the pizzeria, at which time pizza will be made. In our analogy the cash is the pizza and the coupon is the checking account.
pizza coupon
