Scarcity and urgency are principles that motivate a decision through limited availability or limited time. They show up as information about the last item in stock, the number of places left, a countdown to the end of a promotion, or a deadline for how long a price applies. They work because postponing a decision is the most common reason an enquiry never turns into an order. It is essential that they be truthful. A countdown that resets itself after reaching zero, permanently "last items", or a permanent discount off a fictitious original price are misleading commercial practices that carry the risk of a penalty and a near-certain loss of trust once the customer notices. If a real shortage exists, communicate it factually; if it does not, look for another reason to decide now.
See also: Margin and discount promotions, Trust signals, Social proof.
