At the peak of Aurora Hinz’s skincare routine, she was using 10 products, most of them on a daily basis: Two face washes, a toner, a serum, two moisturizers, sheet masks, an exfoliant, and two over-the-counter acne treatments. Hinz had struggled with breakouts for years, and when skincare came into fashion, she decided to stop covering up her acne with makeup, and instead get to the root of the problem with skincare. She typically bought the products from brands like Cosrx, Innisfree, and Tony Moly, where each item cost her between $10 and $50.

There was a sense in which it seemed more virtuous, Hinz said. Foregoing layers of concealer for “natural” cleansers and creams felt, well, natural. Besides, it was fun: Hinz, who is Korean, enjoyed getting swept up in new Korean beauty trends that were just making their way overseas when she was in high school. But after years of trying to calm her skin with several hundred dollars worth of products and few noticeable results, Hinz saw a dermatologist in 2017, and ditched the bulk of her skincare routine in favor of products prescribed or approved by her doctor. They worked.

“Honestly I think I was just a sucker for all the marketing, packaging, and branding,” Hinz, 20, said. “None of the products I tried worked as well as whatever the dermatologist has given me. My skin is clearer than it’s ever been.”

It’s difficult to pinpoint exactly when skincare—a term that’s come to signify far more than merely caring for one’s skin—became the pervasive cultural trend it is today. But Korea is a good place to start: K-Beauty began to secure a foothold in American markets around 2015, when the export value of Korean beauty products to the United States climbed by 60 percent compared to the year before. One of its most popular exports was a 10-step skincare routine, which involves, in this precise order: an oil cleanser, a foam or cream cleanser, a toner, an essence, an emulsion, a serum, a sheet mask, eye cream, moisturizer, and, finally, sunscreen. If you purchase all 10 steps together—as you can on sites like Soko Glam and Peach & Lily—the kit can cost anywhere between $199 and $273.

The lengthy regimen provided American women with the basic scaffolding to create their own personalized skincare routines, swapping out products for the next must-have items, or simply the ones friends swore by. Since then, the industry has only ballooned, inflated by influencers on Instagram and YouTube as well as the multimillion- and billion-dollar brands many of them endorse, like Glossier and Drunk Elephant, where a 1-oz. Vitamin C serum costs $90. According to a widely cited 2017 survey from the skincare retailer SkinStore, the average American woman spends about $2,900 a year on skincare and makeup, and replaces her products about every three months.