Level 1 — System Context

C4 Level 1: System Context Diagram

Purpose

The Context diagram is the most zoomed-out view. It shows:

  • The system being built (Train.md)
  • Who uses it (actors/personas)
  • What external systems it interacts with

Audience: Everyone — technical and non-technical stakeholders alike.

Train.md Context Diagram

flowchart LR
  subgraph External
    search["🔍 Search Engines"]
    github["📦 GitHub"]
  end
  
  dev["👨‍💻 Developer"] --> web["📄 Train.md\n(Documentation Site)"]
  pm["📋 Product Manager"] --> web
  web --> search
  web -.->|hosted on| github

Elements

ElementTypeDescription
DeveloperPersonPrimary user; reads/writes documentation
Product ManagerPersonConsumes documentation for planning
Train.mdSystemStatic documentation site
Search EnginesExternal SystemIndex and surface content
GitHubExternal SystemHosts source and may serve pages

Checklist for Context Diagrams

  • All user types/personas identified
  • External systems and integrations listed
  • Relationships labeled with purpose
  • Scope boundary is clear