The pavement is almost too hot to touch. Somewhere between a café table and a boutique window, a woman’s Havaianas flip-flops slap softly against her heels, the rhythm only interrupted when she pauses to check her phone. Across the street, a model in leather slides exits a runway rehearsal, looking effortlessly polished. Meanwhile, a vendor stacks towers of plastic thongs like candy on a quiet beach in Rio. Humble, inexpensive, and sometimes controversial, flip-flops carry stories that extend far beyond sand and sea. They reveal more about taste, class, politics, and environmental issues than you might expect, and by 2025, they are just as likely to be seen on the runway as they are at the corner shop.