Core Building Blocks
How bytes on a socket become a handled request, how data lives on disk, and how traffic reaches the right server.
The five foundational pieces every backend system is built from. Understand these first — everything else stacks on top.
Topics
| Chapter | What It Covers |
|---|---|
| APIs | REST, GraphQL, gRPC, API Gateway, design patterns |
| Databases | SQL vs NoSQL, ACID, indexing, query optimization, internals |
| Caching | Strategies, levels, invalidation, distributed caching, CDN |
| Load Balancing | Types, algorithms, high availability |
| Proxies | Forward vs reverse, use cases, tunneling |
Why Start Here
Every system design interview eventually touches these. You can't talk about scaling without understanding load balancers. You can't discuss consistency without knowing how databases work. You can't design an API without understanding the tradeoffs between REST, GraphQL, and gRPC.
These are the atoms. Everything else is molecules.