A good diagram can explain a complex system better than pages of text. But many technical diagrams confuse more than they clarify. Here's how to create diagrams that actually help people understand.
Know your audience
Different audiences need different diagrams. Before you start drawing, ask:
- Who will use this diagram?
- What do they already know?
- What do they need to understand?
- How will they use this information?
A diagram for executives should look different from one for developers. Executives need high-level concepts. Developers need implementation details.
Choose the right diagram type
Different information needs different diagram types:
- Flowcharts: Show processes and decision points
- Entity-relationship diagrams: Show data structures and relationships
- Sequence diagrams: Show interactions between components over time
- Architecture diagrams: Show system components and their connections
- State diagrams: Show different states a system can be in
Pick the type that best fits what you're trying to explain.
Focus on one concept
A common mistake is trying to show everything in one diagram. This creates visual overload. Instead:
- Decide on the main point you want to communicate
- Include only elements that support that point
- Create multiple diagrams if needed
It's better to have three clear diagrams than one confusing one.
Use consistent visual language
Your diagram should follow visual conventions:
- Use the same symbol for the same type of component
- Keep sizes consistent for items of equal importance
- Use color with purpose, not just for decoration
- Align elements to create visual order
If you use a blue rectangle for a database in one part of your diagram, don't use a blue rectangle for a service in another part.
Label clearly
Labels make or break a diagram:
- Use concise, specific labels
- Position labels consistently
- Make sure text is readable at the intended viewing size
- Consider adding brief descriptions for complex elements
"Payment Processing Service" is better than "Service" or "System that processes payments from users and validates them against the payment provider API."
Show direction and flow
Most technical systems have direction:
- Use arrows to show data or process flow
- Consider numbering steps if sequence matters
- Use consistent arrow styles for similar types of flow
Different arrow styles can indicate different types of relationships: data flow, API calls, dependencies, etc.
Include a legend
Don't assume everyone knows what your symbols mean:
- Add a legend explaining symbols and colors
- Define any abbreviations or technical terms
- Explain different types of connections
A good legend makes your diagram accessible to a wider audience.
Use layers of detail
Complex systems need different levels of detail:
- Start with a high-level overview
- Create more detailed diagrams for specific components
- Link diagrams together for navigation
This lets readers zoom in on areas they care about without getting overwhelmed.
Test with real users
The true test of a diagram is whether people can understand it:
- Show your diagram to someone from your target audience
- Ask them to explain what they see
- Note where they get confused
- Revise based on their feedback
If they can't explain it back to you, your diagram needs work.
Tools for creating diagrams
You don't need to be an artist to create good diagrams:
- General purpose: Lucidchart, draw.io, Miro
- Developer-focused: PlantUML, Mermaid, C4 Model tools
- AI-assisted: resetDocs, which can generate diagrams from text descriptions
The best tool is the one you'll actually use.
Final thoughts
Good diagrams take time, but they save more time in the long run. They reduce misunderstandings, speed up onboarding, and help teams work together more effectively.
Remember: the goal isn't to create art. The goal is to help people understand complex systems more easily. If your diagram does that, it's successful.