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Over the last 13 months, the youngest member of the Kardashian/Jenner clan has built a business empire for herself, with an estimated $10 million in personal earnings from sales of branded merchandise, which ranges from Kylie Lip Kits (pairs of matte liquid lipstick and lip liner that retail for $29) to Kyshadows and Kyliners (eye shadows and eye liners) in a multitude of colors and themes. She offers them exclusively on her own website in limited time frames for as long as stocks last.

Appetites are stoked to near fever pitch by video clips of Ms. Jenner applying the cosmetics or giving tutorials using them. Those clips are posted to Snapchat, with hints dropped on Twitter or Instagram as to when these products may be available. Although no one knows exactly how many followers she has, a spokesman for Snapchat said in August that Ms. Jenner was the most followed person on the platform. So when the latest batch of new stock does go live on her website, all products are sold, on average, in less than a minute. Then the process begins again.

Ms. Jenner is part of a growing cohort of both individuals and brands that have embraced the sales strategy known as the “drop.” It works like this: A seller controls the release of exclusive new items outside the traditional fashion cycle, cleverly marketing the impending arrival of the product to build demand. Pioneered almost two decades ago by the American skate wear brand Supreme, which took its cues from the Japanese street wear scene, the trend has gained particular momentum in recent years thanks to its adoption by some in the booming limited-edition sneaker industry: Kanye West’s Yeezy line with Adidas, for example, and Nike’s Air Jordans. It is also at the heart of the limited-edition designer collaborations championed by retailers like H&M and Target. Even Snapchat itself tried to jump on the bandwagon last month when it began exclusive sales of its new Spectacles glasses via randomly placed bright yellow vending machines, giving no indication of where they would crop up next. The overwhelming majority of drop customers, whatever the product, are younger than 30.