Documenting design decisions is a vital part of software architecture. It records key choices so they are understood, accessible, and useful for onboarding, troubleshooting, and future updates. This helps architects justify decisions, track changes, and preserve architectural integrity over the system’s lifecycle.

Good documentation should capture both technical and non-technical aspects, including the reasons for a choice, alternatives considered, and potential consequences. Clear records keep the architecture coherent as it evolves and improve communication among stakeholders. How to document key architectural decisions.

1. Identify the Decision Context: document the problem and requirements.

2. Describe the Decision: summarize the choice and its impact.

3. List Alternatives Considered: note other options reviewed.

4. Explain the Rationale: give reasons for the chosen option.

5. State the Impact: outline trade-offs, risks, or benefits.

6. Review and Update: revise decisions as the system evolves.

A decision log tracks key architectural choices over time, recording what was decided, why, and with what result. It provides transparency, prevents confusion, and helps new team members understand the reasoning behind past decisions.

A design rationale explains the reasons for specific choices, alternatives considered, and trade-offs made. Together, decision logs and design rationales support long-term maintainability, ensuring the architecture's vision stays clear and consistent as teams or technologies change.

By following these guidelines, teams can effectively document their architectural decisions and ensure that key information is preserved for the future.