On May 17, Shein — pronounced "she-in” — ended Amazon’s 152-day streak as the most downloaded shopping app in the U.S., a remarkable feat for any seven-year-old clothing brand, let alone one most Americans over 30 still haven’t heard of.

The kids, though, are all over it. As with so many online phenomena, Gen Z and young millennial shoppers have propelled Shein’s rise, in thrall to the company’s never-ending, always-changing catalog of clothes at prices that stretch even the most meager allowance.

One recent Thursday, the app debuted 6,239 new items, including a floral backless halter top ($5; ¥550), purple dinosaur-print pajamas ($10) and a prom-perfect fitted butterfly-sleeve dress with pearl trim ($22). Earlier this year, a U.K. blogger crowed that she’d paid just £100 (¥15,500) for more than 30 Shein bikinis, a clearly impractical number of swimsuits until you remember that social media audiences demand novelty above all.