The Three Layers That Rule Everything

The Three Layers That Make Every System Work

System design has three layers, like building a city.

Layer 1: Architecture (Master Plan) 
                ↓ 
Layer 2: Components (Buildings) 
                ↓ 
Layer 3: Modules (Rooms)

Layer 1: Architecture

The master plan. You decide where to put your database, API servers, and CDN. Just like zoning a city into residential, commercial, and industrial areas.

Layer 2: Components

The actual buildings. In your authentication area, you need a web server, database, and cache working together. Each has a clear job.

Layer 3: Modules

The rooms inside each building. Your authentication component has login, password reset, and verification modules,

Each does one thing well.

The Key Insight

Each layer talks to others through clear channels.

Your login module doesn't randomly access the payment database. There are boundaries and rules.

This three-layer approach works for Instagram, Netflix, or any system you build. The structure stays the same, the contents change.