Welcome to Module 1 of the C4 Model learning course — the essential starting point where we build a solid understanding of why this approach exists and how it fundamentally changes the way teams visualize and communicate software architecture.
The C4 Model, created by Simon Brown between 2006 and 2011, is a lightweight, developer-friendly, and hierarchical method for visualizing software architecture. It provides a simple yet powerful set of abstractions and diagram types that allow you to create clear, consistent, and audience-appropriate diagrams — without the complexity or rigidity of full UML or ad-hoc “boxes and lines” sketches.
At its heart, the C4 Model addresses a widespread pain point in software teams: most architecture documentation is either missing, inconsistent, outdated, overwhelming, or fails to communicate effectively to different audiences (from executives and product managers to developers and operations teams). Traditional approaches often suffer from the “blank canvas” problem — people start drawing without structure, leading to ambiguous, hard-to-maintain, or overly cluttered diagrams. The C4 Model fixes this by offering:
- A clear hierarchy of abstractions that lets you “zoom in” from the big picture to fine details
- Just a small set of core elements (Person, Software System, Container, Component, and Relationships)
- Notation independence — use any style of boxes/lines (simple sketches, PlantUML, Draw.io, Miro, etc.)
- Tooling independence — from whiteboards to code-based solutions like Structurizr or C4-PlantUML
- Emphasis on communication and understanding over exhaustive documentation
The Four Core Levels (the “C4”)
The model is built around four progressive levels of detail:
- Level 1: System Context — The highest-level “big picture” view. Your entire software system is shown as a single box, surrounded by its users (Persons) and external systems it interacts with. Ideal for non-technical stakeholders and onboarding.
- Level 2: Containers — Zooms inside the software system to reveal the major deployable/runnable building blocks (web applications, mobile apps, APIs, databases, message queues, etc.). Highlights chosen technologies and inter-container interactions.
- Level 3: Components — Zooms into a single container to show its internal logical modules, services, libraries, or subsystems — focusing on responsibilities and interfaces without diving into code.
- Level 4: Code — The most granular level, showing implementation details (e.g., UML class diagrams, ERDs, or actual code structure). Used selectively when needed for deep technical clarity.
Supporting Views
In addition to the core hierarchy, the C4 Model defines three supplementary diagram types for broader or specialized perspectives:
- System Landscape — A zoomed-out enterprise view showing multiple software systems and their high-level relationships across the organization.
- Dynamic — Runtime-focused diagrams illustrating how elements interact for specific scenarios or use cases (similar to simplified sequence diagrams).
- Deployment — Maps containers to infrastructure (servers, cloud regions, networks, Kubernetes clusters, etc.), bridging logical architecture with physical runtime.
By the end of this module, you’ll understand why the C4 Model has been widely adopted by thousands of teams worldwide — because it is pragmatic, scalable, maintainable, and focused on telling the right story to the right audience at the right level of detail.
This foundation prepares you perfectly for the hands-on modules ahead, starting with creating your first System Context Diagram in Module 2.
Let’s begin building your C4 knowledge — one clear, zoomable layer at a time!