Short answer: You design scalable backend infrastructure and disciplined mobile clients that assume failure and retries. Explain like I’m 5 years old: 1. Millions of phones want to talk at once. 2. One computer would get tired. 3. So we use many computers. 4. Phones wait their turn. 5. Everyone still gets an answer. Correct explanation (engineer-level, simplified) In production, mobile clients never talk directly to a single backend server. Requests flow through CDNs, API gateways, and load bala