Introduction to System Design

System design is crucial for building scalable applications. Let's cover fundamental concepts.

Key Concepts

Scalability

Vertical Scaling: Add more resources to existing machine Horizontal Scaling: Add more machines

Load Balancing

Distribute traffic across multiple servers:

User → Load Balancer → Server 1
                 → Server 2
                 → Server 3

Caching

Store frequently accessed data:

• CDN: Static assets
• Redis/Memcached: Application data
• Browser Cache: Client-side data

Database

Choose based on needs:

| Use Case | Database | |----------|----------| | Relational data | PostgreSQL | | Flexible schema | MongoDB | | Caching | Redis | | Search | Elasticsearch | | Analytics | ClickHouse |

Design Patterns

Microservices

Break down into independent services.

Event-Driven Architecture

Use message queues for async communication.

CQRS

Separate read and write operations.

Common Interview Questions

1. Design URL shortener
2. Design Twitter feed
3. Design Uber backend
4. Design chat system

Conclusion

Practice designing systems. Start with requirements, then scale up.