System Design

System design interviews test whether you can start from vague requirements, size the problem, and make choices you can defend. This track has two parts.

1. Building blocks. Load balancing, caching, databases, replication, partitioning, queues and consistency models, each explained by how it fails and how it changes with scale.
2. Worked problems. Every problem follows the same eight steps, so you always know where you are: requirements, estimates, API, data model, high level design, deep dives, bottlenecks, tradeoffs.