🌍 System Design

🏗️ Core Foundations

• Scalability: Vertical vs Horizontal, Bottlenecks.
• Availability & Reliability: The "Nines," Fault Tolerance.

🚦 Traffic Management

• Load Balancing: Algorithms, L4 vs L7.
• DNS (Domain Name System): How the internet finds you.
• CDN (Content Delivery Network): Speeding up content globally.

💾 Data Layer

• Databases: SQL vs NoSQL: Choosing the right storage.
• Database Indexing: B-Trees, LSM Trees, and Speed.
• Sharding & Replication: Scaling your database.
• Caching: Strategies (Write-through) and Eviction (LRU).

🧩 Distributed Systems Theory

• CAP Theorem: Consistency vs Availability.
• Consistent Hashing: The Ring Architecture.

🏛️ Architecture & Communication

• Microservices: Decoupling your system.
• Communication Protocols: REST vs gRPC vs WebSockets.
• Message Queues: RabbitMQ vs Kafka.
• API Gateway & Rate Limiting: The Front Door.

📐 Design

• HLD, LLD & UML: Documentation standards and Diagrams.