Excluding and Consuming. To make this distinction, two concepts are employed: exclusion and consumption. Exclusion refers to the degree of control that both the buyer and seller have over a particular commodity; in other words, how easy is it to exclude users or service? Most goods are like a bag of groceries; for a buyer to walk out of a supermarket with a bag of groceries requires that both the buyer and seller agree to a price. In this case (which is the most common one in the real world), the seller exercises a high level of exclusionary control.