Many sites that sell either products or services have recently started displaying X number still available or X items left in their product messaging.

Threadless,  an online T-Shirt Retailer displays “X Left” once a T-shirts stock volumes becomes low.

This pushes people to purchase more quickly, before Threadless runs out of your size.

We also see this with many of the Travel Consolidators, like Orbitz and Travelocity, where they use Scarcity to try and persuade consumers to “act now” before supply is gone or the price increases.

Orbitz uses Scarcity to try and persuade consumers to “Act Fast – Only X number left”

Below is how Travelocity highlights the “X number left”.

The practice of exposing low quantities of a product on e-commerce sites is a very powerful element of the Scarcity principle, which feeds into the consumer’s psychological need to compete with others for an item, which in turn makes that item more attractive to them.