Music alone hasn’t driven the worldwide popularity of K-pop bands like BTS, SuperM, NCT 127 and Blackpink. South Korea’s K-pop companies employ highly effective promotional strategies and market a wide array of branded merchandise — from Bluetooth-enabled light sticks to fuzzy slippers, cosmetics and even food products like fish sticks — that encourages fans to show their devotion by opening up their wallets. These tactics have helped grow the South Korean music industry into a $5.5 billion business — with North America its fastest-growing export market — and are teaching the wider music industry valuable lessons in how to develop what was once a niche musical style into a global behemoth.