L LearnViaNotes @learnvianotes · November 3, 2026 · A complete reference built from your course notes, whiteboard sessions, and case study images. Every concept defined. Every trade-off explained. Every case study dissected.
Three Levels of Design
High-Level Design (HLD): How systems interact — servers, databases, APIs, protocols, data flow.Low-Level Design (LLD): Classes, functions, data structures, algorithms, code-level decisions.System Principles: Scalability, fault tolerance, consistency, availability — the why behind every decision.
What Makes a Good System
A production-grade system must be:Scalable — handles growth without degradingFault tolerant — survives component failureExtensible — easy to add features without rewritesObservable — logs, metrics, tracing, alertingDecoupled — services don't know each other's internals
Scaling → Load Balancing → Caching → Sharding → Microservices → Case Studies
Interview Framework: For every system, practice: (1) clarify requirements, (2) estimate scale, (3) HLD sketch, (4) deep dive on the bottleneck, (5) discuss trade-offs. That's the exact structure top candidates use.
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