Picture a company that gives away its main product for free yet still makes billions. Or one that charges one group a fat fee while almost paying another group to join. Under old‑school competition law, these moves might look like predatory pricing or gouging. But for platforms like Uber, Airbnb, or credit cards, these odd pricing patterns are often what make the whole system work. Watchdogs that miss this multi‑sided logic risk breaking the very markets they want to protect. This chapter explains why platform markets need fresh thinking – and how to avoid expensive mistakes.