# Software Architecture Guide

Software architecture is the set of big decisions that shape a system and are hard to change later. This site explains those decisions in plain language.

**Who it is for:** developers, product owners, and anyone who joins a project and has to understand or start its architecture. You do not need to be an architect.

**What you find here**

- **Concepts:** short articles on one idea each, such as quality scenarios or architecture decisions. Every article starts with "In short" and lists the public sources it is written from.
- **Guides:** how to start the architecture of a project, step by step, and what to do when the basics are missing. Start with [Step 4: Make quality requirements concrete](https://arc.fuet.ch/guides/s04-quality-requirements.md).
- **Review checklist:** checks for an [arc42](https://arc42.org) architecture document, grouped by section. See the [arc42 checklist](https://arc.fuet.ch/review/arc42.md).
- **Glossary:** all [concepts from A to Z](https://arc.fuet.ch/glossary.md).

**For AI assistants:** read [llms.txt](https://arc.fuet.ch/llms.txt). Every page also exists as Markdown.