# Directory structure ``` . ├── book.json ├── README.md ├── SUMMARY.md ├── chapter-1/ | ├── README.md | └── something.md └── chapter-2/ ├── README.md └── something.md ``` An overview of what each of these does: | File | Description | | -------- | ----------- | | `book.json` | Stores [configuration](config.md) data (__optional__) | | `README.md` | Preface / Introduction for your book (**required**) | | `SUMMARY.md` | Table of Contents | ### Sub-directory