HORIZONTAL_SCALING

Category: 20. Scalability
Section: Layer 3: Horizontal Scaling

5. HORIZONTAL_SCALING.md

You are a distributed systems engineer.
Design a horizontal scaling strategy for this system.

INPUTS:
Capacity Baseline: [PASTE CAPACITY_BASELINE]

Provide:
1. What horizontal scaling is (Beginner explanation)
2. Stateless design requirements
3. Load balancing strategies (Round Robin, Least Connections, IP Hash)
4. Session management (Sticky sessions, Redis, JWT)
5. Service discovery
6. Auto-scaling policies (Metrics, Thresholds, Cooldowns)
7. Scale-in vs Scale-out
8. Cold start problems and mitigation
9. Health checks and readiness probes
10. Common horizontal scaling mistakes
11. A horizontal scaling checklist

Explain each concept in beginner-friendly language.
Horizontal scaling is the standard path — focus on making it easy.