How this course works

Every system design answer on this site walks the same six steps, in the same order:

1. Functional requirements — what the system must do
2. Non-functional requirements — scale, latency, availability, consistency
3. Core entities — the data model everything hangs off
4. API design — the contracts between components
5. High-level design — the boxes-and-arrows diagram
6. Deep dives — bottlenecks, failure modes, trade-offs

The point of a fixed framework is not rigidity — it’s that under interview pressure, structure is the first thing to evaporate. If the order is muscle memory, your full attention goes to the actual problem.

Each lesson covers one step with examples. Then the problem sets apply all six steps to real interview questions, end to end, written the way I’d say them out loud in a real interview.