Flash sales are limited-time promotional offers with significant discounts. Initially used primarily in supermarkets during promotional events, these sales were very short, sometimes lasting only a few minutes. With the rise of online shopping, flash sales have expanded their reach. Now, their duration varies from a few hours to a few days, and some major online retailers even organize them regularly. The main objective of a flash sale is to create a sense of urgency among consumers, encouraging them to quickly seize an opportunity before it disappears. In the online retail sector, this sense of urgency is often reinforced by a countdown timer displaying the remaining time to take advantage of the offer. For example, a flash sale in the automotive sector might attract customers by offering special deals on vehicles for a limited time. Amazon, for its part, regularly advertises flash sales to attract shoppers with exceptional offers on a wide range of products. Similarly, magazine or newspaper subscriptions may be subject to flash sales, encouraging readers to subscribe by taking advantage of attractive rates for a limited time.