How should you approach a system design interview?

Start by clarifying functional requirements, users, traffic, data volume, consistency needs, availability targets, security constraints, and the most important quality attributes. State assumptions when information is missing.

Then propose a simple high-level design, define APIs and data ownership, identify likely bottlenecks, and evolve the design for scaling, caching, asynchronous processing, resilience, observability, and security as required. Explain trade-offs instead of presenting one architecture as universally correct.