Why using up selling?

Why using up selling?
Up-selling is a sales technique whereby a salesman attempts to have the customer purchase more expensive items, upgrades, or other add-ons in an attempt to make a more profitable sale. Up-selling usually involves marketing more profitable services or products, but up-selling can also be simply exposing the customer to other options he or she may not have considered previously. Up-selling can imply selling something additional, or selling something that is more profitable or otherwise preferable for the seller instead of the original sale.Ex.: selling an extended service contract for an applianceUp-selling is cheap to implement, develops customer relationships and can dramatically increase revenue.