What is system design?
Why Interviewers Ask This
Foundational questions like this help interviewers calibrate the rest of the interview. A confident, accurate answer signals that you have solid System Design basics — a prerequisite for any developer role.
Answer
System design is the process of defining the architecture, components, modules, interfaces, and data flow of a system to satisfy specified requirements. It bridges the gap between high-level requirements and low-level implementation details. In software engineering, system design involves making decisions about: Architecture — monolith vs microservices, client-server vs peer-to-peer; Data storage — which databases, how to structure data, replication strategy; Scalability — how the system handles growth in users, data, and traffic; Reliability — how the system behaves when components fail; Performance — latency, throughput, response times; Security — authentication, authorization, encryption. System design interviews evaluate a candidate's ability to think at scale and make informed engineering trade-offs. The process typically involves: clarifying requirements, estimating scale (capacity planning), designing high-level architecture, deep-diving into components, identifying bottlenecks, and discussing trade-offs. There is no single "correct" answer — good system design is about demonstrating sound reasoning and awareness of constraints.
Common Mistake
Many candidates answer correctly but can't explain the 'why'. Always be prepared to justify your answer with a concrete example or use case from your System Design experience.