https://bytebytego.com/courses/system-design-interview/scale-from-zero-to-millions-of-users

Single Server

DB

Scaling → Horizontal Scaling → Load Balancer

Web Tier - Failover

DB Tier - Replication - Primary/Replicas

Improve Read Performance - Cache

Web Request Cache

Static Content Cache - CDN

Stateless Web Tier - No state on server & Move state to a shared storage

From

To