Choices and persuasion
Scarcity
Also called Scarcity principle, Fear of missing out
People value things more when they seem rare or about to run out, and act faster when time or stock is limited.
Something hard to get looks more desirable, and a deadline makes waiting feel like losing. Both push people to decide now.
Real limits are worth showing: the last seats at a price, a sale that genuinely ends. They help people decide and avoid regret.
In practice
A booking site that shows 'two rooms left at this price' when that's true helps people decide before the price changes.
Common mistake
Fake countdown timers and invented stock levels. They're among the most reported dark patterns, regulators act on them, and people who catch one stop believing every real limit you show.
Where it comes from
Stephen Worchel, Jerry Lee and Akanbi Adewole showed in 1975 that cookies from a nearly empty jar were rated more desirable. Robert Cialdini made scarcity one of his principles of influence in Influence (1984).